Document and Entity Information - shares	9 Months Ended
Document and Entity Information - shares	Sep. 30, 2017	Oct. 19, 2017
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Sep. 30, 2017
Entity Registrant Name	Employers Holdings, Inc.
Entity Central Index Key	0001379041
Current Fiscal Year End Date	--12-31
Entity Well Know Seasoned Issuer	Yes
Entity Voluntary Filers	No
Entity Current Reporting Status	Yes
Entity Filer Category	Large Accelerated Filer
Entity Common Stock Shares Outstanding		32,430,616
Document Fiscal Year Focus	2017
Document Fiscal Period Focus	Q3

Consolidated Balance Sheets - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Available for sale:
Fixed maturity securities at fair value (amortized cost $2,360.6 at September 30, 2017 and $2,305.9 at December 31, 2016)	$ 2,416,100	$ 2,344,400
Equity securities at fair value (cost $119.3 at September 30, 2017 and $116.1 at December 31, 2016)	203,200	192,200
Short-term investments at fair value (amortized cost $5.5 at September 30, 2017 and $16.0 at December 31, 2016)	5,500	16,000
Total investments	2,624,800	2,552,600
Cash and cash equivalents	69,400	67,200
Restricted cash and cash equivalents	1,100	3,600
Accrued investment income	19,300	20,600
Premiums receivable (less bad debt allowance of $9.9 at September 30, 2017 and $9.8 at December 31, 2016)	331,500	304,700
Reinsurance recoverable for:
Paid losses	7,800	8,700
Unpaid losses	553,100	580,000
Deferred policy acquisition costs	48,100	44,300
Deferred income taxes, net	42,800	59,400
Property and equipment, net	15,000	22,200
Intangible assets, net	8,000	8,200
Goodwill	36,200	36,200
Contingent commission receivable—LPT Agreement	31,100	31,100
Unsettled sales of investments	21,400	0
Other assets	25,800	34,600
Total assets	3,835,400	3,773,400
Claims and policy liabilities:
Unpaid losses and loss adjustment expenses	2,298,900	2,301,000
Unearned premiums	331,100	310,300
Total claims and policy liabilities	2,630,000	2,611,300
Commissions and premium taxes payable	53,000	48,800
Accounts payable and accrued expenses	19,800	24,200
Deferred reinsurance gain—LPT Agreement	166,400	174,900
Notes payable	20,000	32,000
Other liabilities	29,100	41,600
Total liabilities	2,918,300	2,932,800
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.01 par value; 150,000,000 shares authorized; 56,521,284 and 56,226,277 shares issued and 32,423,929 and 32,128,922 shares outstanding at September 30, 2017 and December 31, 2016, respectively	600	600
Preferred stock, $0.01 par value; 25,000,000 shares authorized; none issued	0	0
Additional paid-in capital	377,200	372,000
Retained earnings	832,400	777,200
Accumulated other comprehensive income, net of tax	90,600	74,500
Treasury stock, at cost (24,097,355 shares at September 30, 2017 and December 31, 2016)	(383,700)	(383,700)
Total stockholders’ equity	917,100	840,600
Total liabilities and stockholders’ equity	$ 3,835,400	$ 3,773,400

Consolidated Balance Sheets (Parentheticals) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Available for sale:
Fixed maturity securities, amortized cost	$ 2,485,400	$ 2,438,000
Available for sale, short-term investments, at amortized cost	5,500	16,000
Premiums receivable, bad debt allowance	9,900	9,800
Reinsurance Recoverables on Unpaid Losses, Allowance	$ 0	$ 0
Stockholders' equity
Common stock, par value (in dollars per share)	$ 0.01	$ 0.01
Common stock, shares authorized (in shares)	150,000,000	150,000,000
Common stock, shares issued (in shares)	56,521,284	56,226,277
Common stock, shares outstanding (in shares)	32,423,929	32,128,922
Preferred stock, par value (in dollars per share)	$ 0.01	$ 0.01
Preferred stock, shares authorized (in shares)	25,000,000	25,000,000
Preferred stock, shares issued (in shares)	0	0
Treasury stock, at cost (in shares)	24,097,355	24,097,355
Debt Securities [Member]
Available for sale:
Fixed maturity securities, amortized cost	$ 2,360,600	$ 2,305,900
Equity Securities [Member]
Available for sale:
Fixed maturity securities, amortized cost	119,300	116,100
Short-term Investments [Member]
Available for sale:
Fixed maturity securities, amortized cost	$ 5,500	$ 16,000

Consolidated Statements of Income - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Consolidated Statements of Income - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Revenues
Net premiums earned	$ 187,900	$ 173,300	$ 535,000	$ 522,800
Net investment income	18,500	17,900	55,400	54,100
Net realized gains on investments	4,100	1,600	7,400	9,100
Gain on redemption of notes payable	0	0	2,100	0
Other income	400	0	500	600
Total revenues	210,900	192,800	600,400	586,600
Expenses
Losses and loss adjustment expenses	116,900	109,000	332,000	328,000
Commission expense	23,700	21,300	66,700	63,500
Underwriting and other operating expenses	33,600	31,700	102,100	101,600
Interest expense	300	400	1,100	1,200
Other expenses	7,500	0	7,500	0
Total expenses	182,000	162,400	509,400	494,300
Net income before income taxes	28,900	30,400	91,000	92,300
Income tax expense	7,000	7,800	21,100	21,100
Net income	21,900	22,600	69,900	71,200
Comprehensive income
Unrealized gains (losses) arising during the period (net of taxes of $1.6 and $(2.3)) for the three months ended September 30, 2017 and 2016, respectively, and $11.3 and $21.5 for the nine months ended September 30, 2017 and 2016, respectively)	3,000	(4,200)	20,900	39,900
Reclassification adjustment for realized gains in net income (net of taxes of $1.4 and $0.6 for the three months ended September 30, 2017 and 2016, respectively, and $2.6 and $3.2 for the nine months ended September 30, 2017 and 2016, respectively)	(2,700)	(1,000)	(4,800)	(5,900)
Other comprehensive income, net of tax	300	(5,200)	16,100	34,000
Total comprehensive income	22,200	17,400	86,000	105,200
Net realized gains on investments
Net realized gains on investments before impairments	4,100	1,600	7,600	14,400
Other than temporary impairment recognized in earnings	0	0	(200)	(5,300)
Net realized gains on investments	$ 4,100	$ 1,600	$ 7,400	$ 9,100
Earnings per common share (Note 12):
Basic	$ 0.67	$ 0.70	$ 2.15	$ 2.19
Diluted	0.66	0.69	2.12	2.16
Cash dividends declared per common share and eligible RSUs and PSUs	$ 0.15	$ 0.09	$ 0.45	$ 0.27

Conolidated Statements of Comprehensive Income (Parentheticals) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Income Statement Parenthetical [Abstract]
Other comprehensive income (loss), unrealized holding gain (loss) on securities arising during period, tax	$ 1,600	$ (2,300)	$ 11,300	$ 21,500
Other comprehensive income (loss), reclassification adjustment for sale of securities included in net income, tax	$ 1,400	$ 600	$ 2,600	$ 3,200

Consolidated Statements of Stockholders Equity Statement - USD ($) $ in Thousands	Total	Common Stock	Additional Paid-in Capital	Retained Earnings	Accumulated Other Comprehensive Income, Net	Treasury Stock [Member]
Stockholders' equity, shares at Dec. 31, 2015		55,589,454
Stockholders' equity, value at Dec. 31, 2015	$ 760,800	$ 600	$ 357,200	$ 682,000	$ 83,600	$ (362,600)
Stock-based obligations, shares		0
Stock-based obligations, value	$ 4,300	$ 0	4,300	0	0	0
Stock-options exercised, shares	484,829	484,829
Stock-options exercised, value	$ 7,700	$ 0	7,700	0	0	0
Vesting of RSUs and PSUs, net of shares withheld to satisfy minimum tax withholding, shares		50,691
Vesting of RSUs and PSUs, net of shares withheld to satisfy minimum tax withholding, value	(600)	$ 0	(600)	0	0	0
Acquisition of common stock, shares		0
Acquisition of common stock, value	(18,600)	$ 0	0	0	0	(18,600)
Dividends declared, shares		0
Dividends declared, value	(8,700)	$ 0	0	(8,700)	0	0
Net income	71,200	0	0	71,200	0	0
Change in net unrealized gains in investments, net of tax	34,000	$ 0	0	0	34,000	0
Stockholders' equity, shares at Sep. 30, 2016		56,124,974
Stockholders' equity, value at Sep. 30, 2016	850,100	$ 600	368,600	744,500	117,600	(381,200)
Stockholders' equity, shares at Dec. 31, 2015		55,589,454
Stockholders' equity, value at Dec. 31, 2015	$ 760,800	$ 600	357,200	682,000	83,600	(362,600)
Stock-options exercised, shares	586,132
Stockholders' equity, shares at Dec. 31, 2016	56,226,277	56,226,277
Stockholders' equity, value at Dec. 31, 2016	$ 840,600	$ 600	372,000	777,200	74,500	(383,700)
Stock-based obligations, shares		0
Stock-based obligations, value	$ 4,000	$ 0	4,000	0	0	0
Stock-options exercised, shares	169,024	169,024
Stock-options exercised, value	$ 3,300	$ 0	3,300	0	0	0
Vesting of RSUs and PSUs, net of shares withheld to satisfy minimum tax withholding, shares		125,983
Vesting of RSUs and PSUs, net of shares withheld to satisfy minimum tax withholding, value	(2,100)	$ 0	(2,100)	0	0	0
Dividends declared, shares		0
Dividends declared, value	(14,700)	$ 0	0	(14,700)	0	0
Net income	69,900	0	0	69,900	0	0
Change in net unrealized gains in investments, net of tax	$ 16,100	$ 0	0	0	16,100	0
Stockholders' equity, shares at Sep. 30, 2017	56,521,284	56,521,284
Stockholders' equity, value at Sep. 30, 2017	$ 917,100	$ 600	$ 377,200	$ 832,400	$ 90,600	$ (383,700)

Consolidated Statements of Cash Flows - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Operating activities
Net income	$ 69,900	$ 71,200
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	6,200	6,400
Stock-based compensation	3,900	4,300
Amortization of premium on investments, net	11,200	11,400
Allowance for doubtful accounts	100	(1,500)
Deferred income tax expense	7,900	8,500
Net realized gains on investments	(7,400)	(9,100)
Gain on redemption of notes payable	(2,100)	0
Write-off of previously capitalized costs	7,500	0
Change in operating assets and liabilities:
Premiums receivable	(26,900)	(14,500)
Reinsurance recoverable on paid and unpaid losses	27,800	36,100
Current federal income taxes	(5,200)	3,000
Unpaid losses and loss adjustment expenses	2,100	17,500
Unearned premiums	20,800	16,700
Payables and other liabilities	(9,800)	(6,200)
Deferred reinsurance gain—LPT Agreement	(8,500)	(11,700)
Contingent commission receivable—LPT Agreement	0	(1,900)
Other	10,500	1,800
Net cash provided by operating activities	103,800	97,000
Investing activities
Purchase of fixed maturity securities	(403,700)	(325,200)
Purchase of equity securities	(13,800)	(38,800)
Purchase of short-term investments	(8,200)	(8,000)
Proceeds from sale of fixed maturity securities	181,800	111,700
Proceeds from sale of equity securities	14,600	70,200
Proceeds from maturities and redemptions of fixed maturity securities	159,300	145,100
Proceeds from maturities of short-term investments	18,700	0
Net change in unsettled investment purchases and sales	(21,400)	0
Capital expenditures and other	(7,800)	(3,900)
Change in restricted cash and cash equivalents	2,500	(200)
Net cash used in investing activities	(78,000)	(49,100)
Financing activities
Acquisition of common stock	0	(18,600)
Cash transactions related to stock-based compensation	1,200	7,100
Stockholder dividends paid	(14,700)	(8,800)
Redemption of notes payable	(9,900)	0
Payments on capital leases	200	100
Net cash used in financing activities	(23,600)	(20,400)
Net increase in cash and cash equivalents	2,200	27,500
Cash and cash equivalents at the beginning of the period	67,200	56,600
Cash and cash equivalents at the end of the period	$ 69,400	$ 84,100

Basis of Presentation	9 Months Ended
Basis of Presentation	Sep. 30, 2017
Basis of Presentation [Abstract]
Basis of Presentation	Basis of Presentation and Summary of Operations Employers Holdings, Inc. (EHI) is a Nevada holding company. Through its wholly owned insurance subsidiaries, Employers Insurance Company of Nevada (EICN), Employers Compensation Insurance Company (ECIC), Employers Preferred Insurance Company (EPIC), and Employers Assurance Company (EAC), EHI is engaged in the commercial property and casualty insurance industry, specializing in workers' compensation products and services. Unless otherwise indicated, all references to the “Company” refer to EHI, together with its subsidiaries. In 1999, the Nevada State Industrial Insurance System (the Fund) entered into a retroactive 100% quota share reinsurance agreement (the LPT Agreement) through a loss portfolio transfer transaction with third party reinsurers. The LPT Agreement commenced on June 30, 1999 and will remain in effect until all claims under the covered policies have closed, the LPT Agreement is commuted or terminated, upon the mutual agreement of the parties, or the reinsurers' aggregate maximum limit of liability is exhausted, whichever occurs first. The LPT Agreement does not provide for any additional termination terms. On January 1, 2000, EICN assumed all of the assets, liabilities and operations of the Fund, including the Fund's rights and obligations associated with the LPT Agreement. See Note 8. The Company accounts for the LPT Agreement as retroactive reinsurance. Upon entry into the LPT Agreement, an initial deferred reinsurance gain (the Deferred Gain) was recorded as a liability on the Company’s Consolidated Balance Sheets. The Company is entitled to receive a contingent profit commission under the LPT Agreement. The contingent profit commission is estimated based on both actual paid results to date and projections of expected paid losses under the LPT Agreement and is recorded as an asset in the accompanying Consolidated Balance Sheets. The accompanying consolidated financial statements have been prepared in accordance with U.S. generally accepted accounting principles (GAAP) for interim financial information and with the instructions to Form 10-Q and Article 10 of Regulation S-X of the Securities Exchange Act of 1934, as amended. Accordingly, they do not include all of the information and notes required by GAAP for complete financial statements. In the opinion of management, all adjustments (consisting of normal, recurring adjustments) necessary for a fair presentation of the Company’s consolidated financial position and results of operations for the periods presented have been included. The results of operations for an interim period are not necessarily indicative of the results for an entire year. These financial statements have been prepared consistent with the accounting policies described in the Company’s Form 10-K for the year ended December 31, 2016 (Annual Report). The Company considers an operating segment to be any component of its business whose operating results are regularly reviewed by the Company’s chief operating decision maker to make decisions about resources to be allocated to the segment and assess its performance based on discrete financial information. Currently, the Company has one operating segment, workers’ compensation insurance and related services. Use of Estimates The preparation of the consolidated financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and disclosure of contingent assets and liabilities at the date of the consolidated financial statements and the reported amounts of revenues and expenses during the reporting period. As a result, actual results could differ from these estimates. The most significant areas that require management judgment are the estimate of unpaid losses and loss adjustment expenses (LAE), evaluation of reinsurance recoverables, recognition of premium revenue, recoverability of deferred income taxes, and valuation of investments.

New Accounting Standards Level 1 (Notes)	9 Months Ended
New Accounting Standards Level 1 (Notes)	Sep. 30, 2017
New Accounting Standards [Abstract]
New Accounting Standards	New Accounting Standards Recently Issued Accounting Standards In January 2017, the FASB issued ASU Number 2017-04, Intangibles-Goodwill and Other (Topic 350). This update simplifies the measurement of goodwill by eliminating the performance of Step 2 in the goodwill impairment testing. This update allows the testing to be performed by comparing the fair value of a reporting unit with its carrying amount and recognizing an impairment charge when the carrying amount exceeds fair value. Additionally, this update eliminated the requirements of any reporting unit with a zero or negative carrying value to perform Step 2, but requires disclosure of the amount of goodwill allocated to a reporting unit with zero or negative carrying amount of net assets. This update becomes effective for fiscal years beginning after December 15, 2019. The Company does not expect this update to have a material impact to its consolidated financial condition and results of operations. In March 2017, the FASB issued ASU Number 2017-08, Receivables - Nonrefundable Fees and Other Costs (Subtopic 310-20). This update shortens the amortization period on callable debt securities held at a premium to the earliest call date, which now closely aligns the amortization period of premiums and discounts to expectations incorporated in the market pricing on callable debt securities. This update becomes effective for fiscal years beginning after December 15, 2018 and interim periods within those fiscal years, and early adoption is permitted. The Company does not expect that adoption of this standard will have a material impact on its consolidated financial condition and results of operations.

Fair Value of Financial Instruments

9 Months Ended

Sep. 30, 2017

Fair Value of Financial Instruments [Abstract]

Fair Value of Financial Instruments

The carrying value and the estimated fair value of the Company’s financial instruments were as follows:



	September 30, 2017				December 31, 2016
	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value
	(in millions)
Financial assets
Investments	$	2,624.8	$	2,624.8	$	2,552.6	$	2,552.6
Cash and cash equivalents	69.4		69.4		67.2		67.2
Restricted cash and cash equivalents	1.1		1.1		3.6		3.6
Financial liabilities
Notes payable	$	20.0	$	23.0	$	32.0	$	33.0

Assets and liabilities recorded at fair value on the Company's Consolidated Balance Sheets are categorized based upon the levels of judgment associated with the inputs used to measure their fair value. Level inputs are defined as follows:


•	Level 1 - Inputs are unadjusted quoted market prices for identical assets or liabilities in active markets at the measurement date.


•	Level 2 - Inputs other than Level 1 prices that are observable for similar assets or liabilities through corroboration with market data at the measurement date.


•	Level 3 - Inputs that are unobservable that reflect management's best estimate of what willing market participants would use in pricing the assets or liabilities at the measurement date.

The Company uses third party pricing services to assist with its investment accounting function. The ultimate pricing source varies depending on the investment security and pricing service used, but investment securities valued on the basis of observable inputs (Levels 1 and 2) are generally assigned values on the basis of actual transactions. Securities valued on the basis of pricing models with significant unobservable inputs or non-binding broker quotes are classified as Level 3. The Company performs quarterly analyses on the prices it receives from third parties to determine whether the prices are reasonable estimates of fair value, including confirming the fair values of these securities through observable market prices using an alternative pricing source, as it is ultimately management’s responsibility to ensure that the fair values reflected in the Company’s consolidated financial statements are appropriate. If differences are noted in these analyses, the Company may obtain additional information from other pricing services to validate the quoted price.

The Company bases all of its estimates of fair value for assets on the bid prices, when available, as they represent what a third-party market participant would be willing to pay in an arm's length transaction.

For securities not actively traded, third party pricing services may use quoted market prices of similar instruments or discounted cash flow analyses, incorporating inputs that are currently observable in the markets for similar securities. Inputs that are often used in the valuation methodologies include, but are not limited to, broker quotes, benchmark yields, credit spreads, default rates, and prepayment speed assumptions. There were no adjustments to prices obtained from third party pricing services as of September 30, 2017 and December 31, 2016 that were material to the consolidated financial statements.

These methods of valuation will only produce an estimate of fair value if there is objectively verifiable information to produce a valuation. If objectively verifiable information is not available, the Company would be required to produce an estimate of fair value using some of the same methodologies, making assumptions for market-based inputs that are unavailable.

The Company's estimates of fair value for its financial liabilities are based on a combination of the variable interest rates for notes with similar durations to discount the projection of future payments on notes payable. The fair value measurements for notes payable have been determined to be Level 2 at each of the periods presented.

Each of the Company's insurance operating subsidiaries is a member of the Federal Home Loan Bank of San Francisco (FHLB). Members are required to purchase stock in FHLB in addition to maintaining collateral deposits that back any funds advanced. Investment in FHLB stock is recorded at cost, as purchases and sales of these securities are at par value with the issuer. FHLB stock is considered a restricted security and is periodically evaluated by the Company for impairment based on the ultimate recovery of par value. Due to the nature of FHLB stock, its carrying value approximates fair value and was determined by the Company to be Level 3 at each of the periods presented.

The following table presents the items in the Company's Consolidated Balance Sheets that are stated at fair value and the corresponding fair value measurements.



	September 30, 2017						December 31, 2016
	Level 1		Level 2		Level 3		Level 1		Level 2		Level 3
	(in millions)
Fixed maturity securities
U.S. Treasuries	$	—	$	132.6	$	—	$	—	$	127.4	$	—
U.S. Agencies	—		13.4		—		—		12.8		—
States and municipalities	—		700.4		—		—		851.6		—
Corporate securities	—		1,060.3		—		—		956.7		—
Residential mortgage-backed securities	—		363.2		—		—		258.0		—
Commercial mortgage-backed securities	—		91.6		—		—		95.5		—
Asset-backed securities	—		54.6		—		—		35.4		7.0
Total fixed maturity securities	$	—	$	2,416.1	$	—	$	—	$	2,337.4	$	7.0
Equity securities
Industrial and miscellaneous	$	175.6	$	—	$	—	$	167.2	$	—	$	—
Non-redeemable preferred (FHLB stock)	—		—		4.7		—		—		4.9
Other	22.9		—		—		20.1		—		—
Total equity securities	$	198.5	$	—	$	4.7	$	187.3	$	—	$	4.9
Short-term investments	$	—	$	5.5	$	—	$	—	$	16.0	$	—

Certain cash equivalents, principally money market securities, are measured at fair value using the net asset value (NAV) per share. The following table presents cash equivalents at NAV and total cash and cash equivalents carried at fair value on the Company's Consolidated Balance Sheets.



	September 30, 2017		December 31, 2016
	(in millions)
Cash and cash equivalents at fair value	$	30.4	$	9.7
Cash equivalents measured at NAV, which approximates fair value	39.0		57.5
Total cash and cash equivalents	$	69.4	$	67.2

The following table provides a reconciliation of the beginning and ending balances that are measured using Level 3 inputs for the nine months ended September 30, 2017 and 2016.



	Level 3 Securities
	2017			2016
	(in millions)
Beginning balance, January 1	$	11.9		$	—
Transfers (out) of Level 3 ⁽¹⁾	(7.0		)	—
Purchases and sales, net	(0.2		)	4.9
Ending balance, September 30	$	4.7		$	4.9


(1)	Transferred from Level 3 to Level 2 because observable market data became available for the securities.

- Definition

The entire disclosure for the fair value of financial instruments (as defined), including financial assets and financial liabilities (collectively, as defined), and the measurements of those instruments as well as disclosures related to the fair value of non-financial assets and liabilities. Such disclosures about the financial instruments, assets, and liabilities would include: (1) the fair value of the required items together with their carrying amounts (as appropriate); (2) for items for which it is not practicable to estimate fair value, disclosure would include: (a) information pertinent to estimating fair value (including, carrying amount, effective interest rate, and maturity, and (b) the reasons why it is not practicable to estimate fair value; (3) significant concentrations of credit risk including: (a) information about the activity, region, or economic characteristics identifying a concentration, (b) the maximum amount of loss the entity is exposed to based on the gross fair value of the related item, (c) policy for requiring collateral or other security and information as to accessing such collateral or security, and (d) the nature and brief description of such collateral or security; (4) quantitative information about market risks and how such risks are managed; (5) for items measured on both a recurring and nonrecurring basis information regarding the inputs used to develop the fair value measurement; and (6) for items presented in the financial statement for which fair value measurement is elected: (a) information necessary to understand the reasons for the election, (b) discussion of the effect of fair value changes on earnings, (c) a description of [similar groups] items for which the election is made and the relation thereof to the balance sheet, the aggregate carrying value of items included in the balance sheet that are not eligible for the election; (7) all other required (as defined) and desired information.

+ References + Details

Investments

9 Months Ended

Sep. 30, 2017

Investments [Abstract]

Investments

The cost or amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the Company’s investments were as follows:



	Cost or Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in millions)
At September 30, 2017
Fixed maturity securities
U.S. Treasuries	$	130.3	$	2.5	$	(0.2	)	$	132.6
U.S. Agencies	12.8		0.6		—			13.4
States and municipalities	671.0		30.7		(1.3		)	700.4
Corporate securities	1,040.3		22.0		(2.0		)	1,060.3
Residential mortgage-backed securities	360.1		4.8		(1.7		)	363.2
Commercial mortgage-backed securities	91.7		0.5		(0.6		)	91.6
Asset-backed securities	54.4		0.3		(0.1		)	54.6
Total fixed maturity securities	2,360.6		61.4		(5.9		)	2,416.1
Equity securities
Industrial and miscellaneous	102.8		76.4		(3.6		)	175.6
Non-redeemable preferred (FHLB stock)	4.7		—		—			4.7
Other	11.8		11.1		—			22.9
Total equity securities	119.3		87.5		(3.6		)	203.2
Short-term investments	5.5		—		—			5.5
Total investments	$	2,485.4	$	148.9	$	(9.5	)	$	2,624.8



At December 31, 2016
Fixed maturity securities
U.S. Treasuries	$	124.1	$	3.5	$	(0.2	)	$	127.4
U.S. Agencies	11.9		0.9		—			12.8
States and municipalities	833.0		24.7		(6.1		)	851.6
Corporate securities	942.3		18.9		(4.5		)	956.7
Residential mortgage-backed securities	255.9		4.7		(2.6		)	258.0
Commercial mortgage-backed securities	96.1		0.4		(1.0		)	95.5
Asset-backed securities	42.6		—		(0.2		)	42.4
Total fixed maturity securities	2,305.9		53.1		(14.6		)	2,344.4
Equity securities
Industrial and miscellaneous	100.5		67.4		(0.7		)	167.2
Non-redeemable preferred (FHLB stock)	4.9		—		—			4.9
Other	10.7		9.4		—			20.1
Total equity securities	116.1		76.8		(0.7		)	192.2
Short-term investments	16.0		—		—			16.0
Total investments	$	2,438.0	$	129.9	$	(15.3	)	$	2,552.6

The amortized cost and estimated fair value of the Company's fixed maturity securities at September 30, 2017, by contractual maturity, are shown below. Expected maturities differ from contractual maturities because borrowers may have the right to call or prepay obligations with or without call or prepayment penalties.



	Amortized Cost		Estimated Fair Value
	(in millions)
Due in one year or less	$	260.8	$	262.2
Due after one year through five years	715.3		737.1
Due after five years through ten years	692.5		713.7
Due after ten years	185.8		193.7
Mortgage and asset-backed securities	506.2		509.4
Total	$	2,360.6	$	2,416.1

The following is a summary of investments that have been in a continuous unrealized loss position for less than 12 months and those that have been in a continuous unrealized loss position for 12 months or greater as of September 30, 2017 and December 31, 2016.



	September 30, 2017						December 31, 2016
	Estimated Fair Value		Gross Unrealized Losses			Number of Issues	Estimated Fair Value		Gross Unrealized Losses			Number of Issues
	(in millions, except number of issues data)
Less than 12 months:
Fixed maturity securities
U.S. Treasuries	$	64.7	$	(0.1	)	25	$	33.3	$	(0.2	)	14
States and municipalities	38.9		(0.5		)	10	200.9		(6.1		)	50
Corporate securities	211.9		(1.6		)	72	289.5		(4.1		)	101
Residential mortgage-backed securities	165.1		(1.6		)	52	137.5		(2.6		)	51
Commercial mortgage-backed securities	35.6		(0.4		)	13	48.0		(1.0		)	21
Asset-backed securities	26.7		(0.1		)	25	30.1		(0.2		)	20
Total fixed maturity securities	542.9		(4.3		)	197	739.3		(14.2		)	257
Equity securities	17.5		(3.2		)	30	13.6		(0.6		)	28
Total less than 12 months	$	560.4	$	(7.5	)	227	$	752.9	$	(14.8	)	285

12 months or greater:
Fixed maturity securities
U.S. Treasuries	$	2.9	$	(0.1	)	1	$	—	$	—		—
States and municipalities	21.0		(0.8		)	8	—		—			—
Corporate securities	23.5		(0.4		)	10	15.2		(0.4		)	5
Residential mortgage-backed securities	3.5		(0.1		)	3	—		—			—
Commercial mortgage-backed securities	6.3		(0.2		)	4	—		—			—
Total fixed maturity securities	57.2		(1.6		)	26	15.2		(0.4		)	5
Equity securities	4.0		(0.4		)	2	1.7		(0.1		)	5
Total 12 months or greater	$	61.2	$	(2.0	)	28	$	16.9	$	(0.5	)	10

Total available-for-sale:
Fixed maturity securities
U.S. Treasuries	$	67.6	$	(0.2	)	26	$	33.3	$	(0.2	)	14
States and municipalities	59.9		(1.3		)	18	200.9		(6.1		)	50
Corporate securities	235.4		(2.0		)	82	304.7		(4.5		)	106
Residential mortgage-backed securities	168.6		(1.7		)	55	137.5		(2.6		)	51
Commercial mortgage-backed securities	41.9		(0.6		)	17	48.0		(1.0		)	21
Asset-backed securities	26.7		(0.1		)	25	30.1		(0.2		)	20
Total fixed maturity securities	600.1		(5.9		)	223	754.5		(14.6		)	262
Equity securities	21.5		(3.6		)	32	15.3		(0.7		)	33
Total available-for-sale	$	621.6	$	(9.5	)	255	$	769.8	$	(15.3	)	295

The Company determined that unrealized losses on fixed maturities for the nine months ended September 30, 2017 were primarily the result of changes in prevailing interest rates and not the credit quality of the issuers. The fixed maturity securities whose total fair value was less than amortized cost were not determined to be other-than-temporarily impaired given the lack of severity and duration of the impairment, the credit quality of the issuers, the Company’s intent to not sell the securities, and a determination that it is not more likely than not that the Company will be required to sell the securities until fair value recovers to above amortized cost, or principal value upon maturity.

The Company recognized an impairment of $0.2 million (from one equity security) during the nine months ended September 30, 2017. The other-than-temporary impairment recognized during this period was the result of the severity and duration of the change in fair value of this equity security. Certain unrealized losses on equity securities were not considered to be other-than-temporary due to the financial condition and near-term prospects of the issuers, and the Company's intent to hold the securities until fair value recovers to above cost.

Net realized gains on investments and the change in unrealized gains (losses) on fixed maturity and equity securities are determined on a specific-identification basis and were as follows:



	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2017			2016			2017			2016
	(in millions)
Net realized gains on investments
Fixed maturity securities
Gross gains	$	3.5		$	—		$	4.0		$	1.3
Gross losses	(0.7		)	—			(0.8		)	(0.5		)
Net realized gains on fixed maturity securities	$	2.8		$	—		$	3.2		$	0.8
Equity securities
Gross gains	$	1.3		$	1.6		$	4.4		$	14.3
Gross losses	—			—			(0.2		)	(6.0		)
Net realized gains on equity securities	$	1.3		$	1.6		$	4.2		$	8.3
Total	$	4.1		$	1.6		$	7.4		$	9.1

Change in net unrealized gains
Fixed maturity securities	$	(1.9	)	$	(10.2	)	$	17.0		$	43.4
Equity securities	2.4			2.1			7.8			8.9
Total	$	0.5		$	(8.1	)	$	24.8		$	52.3

Net investment income was as follows:



	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2017			2016			2017			2016
	(in millions)
Fixed maturity securities	$	17.4		$	16.9		$	52.4		$	50.8
Equity securities	1.7			1.7			5.2			5.4
Cash equivalents and restricted cash	0.2			0.1			0.4			0.2
Gross investment income	19.3			18.7			58.0			56.4
Investment expenses	(0.8		)	(0.8		)	(2.6		)	(2.3		)
Net investment income	$	18.5		$	17.9		$	55.4		$	54.1

The Company is required by various state laws and regulations to hold securities or letters of credit in depository accounts with certain states in which it does business. These laws and regulations govern not only the amount but also the types of securities that are eligible for deposit. As of September 30, 2017 and December 31, 2016, securities having a fair value of $1,017.7 million and $1,009.7 million, respectively, were on deposit.

Certain reinsurance contracts require the Company's funds to be held in trust for the benefit of the ceding reinsurer to secure the outstanding liabilities assumed by the Company. The fair value of fixed maturity securities and restricted cash and cash equivalents held in trust for the benefit of ceding reinsurers at September 30, 2017 and December 31, 2016 was $25.2 million and $27.2 million, respectively.

Property and Equipment Level 1 (Notes)

9 Months Ended

Sep. 30, 2017

Property and Equipment [Abstract]

Property, Plant and Equipment Disclosure

Property and Equipment

Property and equipment consists of the following:



	As of September 30,			As of December 31,
	2017			2016
	(in millions)
Furniture and equipment	$	1.7		$	2.3
Leasehold improvements	2.9			4.3
Computers and software	54.5			59.0
Automobiles	1.2			1.2
Property and equipment, gross	60.3			66.8
Accumulated depreciation	(45.3		)	(44.6		)
Property and equipment, net	$	15.0		$	22.2

Depreciation expenses related to property and equipment for the nine months ended September 30, 2017 was $6.0 million and for the year ended December 31, 2016 was $8.2 million. Internally developed software costs of $1.8 million and $1.3 million were capitalized during the nine months ended September 30, 2017 and the year ended December 31, 2016, respectively.

Additionally, during the third quarter of 2017, the Company wrote-off $7.5 million of previously capitalized costs relating to the development of information technology capabilities that had not yet been placed in service, which is recognized in Other expenses in the Company's Consolidated Statements of Comprehensive Income. The Company incurred this charge as part of a continual evaluation of its ongoing technology initiatives.

Income Taxes	9 Months Ended
Income Taxes	Sep. 30, 2017
Income Taxes [Abstract]
Income Taxes	Income Taxes Income tax expense for interim periods is measured using an estimated effective tax rate for the annual period. The Company's effective tax rate was 23.2% and 22.9% for the nine months ended September 30, 2017 and 2016, respectively. Tax-advantaged investment income, LPT Reserve Adjustments, Deferred Gain amortization, and certain other adjustments reduced the Company's effective income tax rate below the U.S. statutory rate of 35%.

Liability for Unpaid Losses and Loss Adjustment Expenses

9 Months Ended

Sep. 30, 2017

Liability for Unpaid Losses and Loss Adjustment Expenses [Abstract]

Liability for Unpaid Losses and Loss Adjustment Expenses

The following table represents a reconciliation of changes in the liability for unpaid losses and LAE.



	Three Months Ended					Nine Months Ended
	September 30,					September 30,
	2017			2016		2017			2016
	(in millions)
Unpaid losses and LAE, gross of reinsurance, at beginning of period	$	2,284.9		$	2,332.3	$	2,301.0		$	2,347.5
Less reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE	559.8			598.8		580.0			628.2
Net unpaid losses and LAE at beginning of period	1,725.1			1,733.5		1,721.0			1,719.3
Losses and LAE, net of reinsurance, incurred during the period related to:
Current period	119.7			111.1		341.0			343.1
Prior periods	(0.2		)	0.8		(0.5		)	(1.5		)
Total net losses and LAE incurred during the period	119.5			111.9		340.5			341.6
Paid losses and LAE, net of reinsurance, related to:
Current period	23.5			23.7		45.2			42.8
Prior periods	75.3			83.2		270.5			279.6
Total net paid losses and LAE during the period	98.8			106.9		315.7			322.4
Ending unpaid losses and LAE, net of reinsurance	1,745.8			1,738.5		1,745.8			1,738.5
Reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE	553.1			591.5		553.1			591.5
Unpaid losses and LAE, gross of reinsurance, at end of period	$	2,298.9		$	2,330.0	$	2,298.9		$	2,330.0

Total net losses and LAE included in the above table excludes the impact of the aggregate of amortization of the deferred reinsurance gain—LPT Agreement, LPT Reserve Adjustments, and LPT Contingent Commission Adjustments, which totaled $2.5 million and $3.0 million for the three months ended September 30, 2017 and 2016, respectively, and $8.5 million and $13.6 million for the nine months ended September 30, 2017 and 2016, respectively (Note 8).

The change in incurred losses and LAE attributable to prior periods was related to the Company's assigned risk business for the nine months ended September 30, 2016.

LPT Agreement	9 Months Ended
LPT Agreement	Sep. 30, 2017
LPT Agreement [Abstract]
LPT Agreement	LPT Agreement The Company is party to the LPT Agreement under which $1.5 billion in liabilities for losses and LAE related to claims incurred by the Fund prior to July 1, 1995 were reinsured for consideration of $775.0 million. The LPT Agreement provides coverage up to $2.0 billion. The Company records its estimate of contingent profit commission in the accompanying Consolidated Balance Sheets as Contingent commission receivable–LPT Agreement and a corresponding liability is recorded in the accompanying Consolidated Balance Sheets in Deferred reinsurance gain–LPT Agreement. The Deferred Gain is being amortized using the recovery method. Amortization is determined by the proportion of actual reinsurance recoveries to total estimated recoveries over the life of the LPT Agreement, except for the contingent profit commission, which is amortized through June 30, 2024, the date through which the Company is entitled to receive a contingent profit commission under the LPT Agreement. The amortization is recorded in losses and LAE incurred in the accompanying consolidated statements of comprehensive income. Any adjustments to the Deferred Gain are recorded in losses and LAE incurred in the accompanying consolidated statements of comprehensive income. The Company amortized $2.5 million and $3.0 million of the Deferred Gain for the three months ended September 30, 2017 and 2016, respectively, and $8.5 million and $8.7 million for the nine months ended September 30, 2017 and 2016, respectively. Additionally, the Deferred Gain was reduced by a further $3.1 million and $1.8 million for the nine months ended September 30, 2016, due to a favorable LPT Reserve Adjustment and a favorable LPT Contingent Commission Adjustment, respectively. The remaining Deferred Gain was $166.4 million and $174.9 million as of September 30, 2017 and December 31, 2016, respectively. The estimated remaining liabilities subject to the LPT Agreement were $445.4 million and $465.5 million as of September 30, 2017 and December 31, 2016, respectively. Losses and LAE paid with respect to the LPT Agreement totaled $742.7 million and $722.7 million from inception through September 30, 2017 and December 31, 2016, respectively.

Notes Payable Level 1 (Notes)

9 Months Ended

Sep. 30, 2017

Notes Payable [Abstract]

Debt Disclosure [Text Block]

Notes Payable

Notes payable is comprised of the following:



	September 30, 2017		December 31, 2016
	(in millions)
Dekania Surplus Note, due April 30, 2034	$	10.0	$	10.0
Alesco Surplus Note, due December 15, 2034	10.0		10.0
ICONS Surplus Note, due May 26, 2034	—		12.0
Balance	$	20.0	$	32.0

EPIC has a $10.0 million surplus note to Dekania CDO II, Ltd. issued as part of a pooled transaction. The note matures in 2034 and became callable by the Company in 2009. The terms of the note provide for quarterly interest payments at a rate 425 basis points in excess of the 90-day LIBOR. Both the payment of interest and repayment of the principal under this note and the surplus notes described in the succeeding two paragraphs are subject to the prior approval of the Florida Department of Financial Services.

EPIC has a $10.0 million surplus note to Alesco Preferred Funding V, LTD issued as part of a pooled transaction. The note matures in 2034 and became callable by the Company in 2009. The terms of the note provide for quarterly interest payments at a rate 405 basis points in excess of the 90-day LIBOR.

EPIC had a $12.0 million surplus note to ICONS, Inc. issued as part of a pooled transaction. This note was redeemed in May 2017 for $9.9 million, resulting in a $2.1 million gain.

Accumulated Other Comprehensive Income

9 Months Ended

Sep. 30, 2017

Accumulated Other Comprehensive Income [Abstract]

Accumulated Other Comprehensive Income, Net

Accumulated Other Comprehensive Income

Accumulated other comprehensive income is comprised of unrealized gains on investments classified as available-for-sale, net of deferred tax expense. The following table summarizes the components of accumulated other comprehensive income:



	September 30, 2017			December 31, 2016
	(in millions)
Net unrealized gains on investments, before taxes	$	139.4		$	114.6
Deferred tax expense on net unrealized gains	(48.8		)	(40.1		)
Total accumulated other comprehensive income	$	90.6		$	74.5

Stock-Based Compensation

9 Months Ended

Sep. 30, 2017

Stock-Based Compensation [Abstract]

Stock-Based compensation

Stock-Based Compensation

The Company awarded restricted stock units (RSUs) and performance share units (PSUs) to certain employees and non-employee Directors of the Company as follows:



	Number Awarded	Weighted Average Fair Value on Date of Grant		Weighted Average Exercise Price		Aggregate Fair Value on Date of Grant
						(in millions)
March 2017
RSUs⁽¹⁾	72,020	$	37.60	$	—	$	2.7
PSUs⁽²⁾	97,440	37.60		—		3.7

May 2017
RSUs⁽¹⁾	11,888	$	40.35	$	—	$	0.5

July 2017
RSUs⁽¹⁾	1,251	43.95		$	—	$	0.1


(1)	The RSUs awarded in March 2017 were awarded to certain employees of the Company and vest 25% on March 15, 2018, and each of the subsequent three anniversaries of that date. The RSUs are subject to accelerated vesting in certain circumstances, including but not limited to: death, disability, retirement, or in connection with change of control of the Company.

The RSUs awarded in May 2017 and July 2017 were awarded to non-employee Directors of the Company and vest on May 25, 2018.


(2)	The PSUs awarded in March 2017 were awarded to certain employees of the Company and have a performance period of two years followed by an additional one year vesting period. The PSU awards are subject to certain performance goals with payouts that range from 0% to 200% of the target awards. The value shown in the table represents the aggregate number of PSUs awarded at the target level.

Commencing in 2017, employees who were awarded RSUs and PSUs are entitled to receive dividend equivalents for eligible awards, payable in cash, when the underlying award vests and becomes payable. If the underlying award does not vest or is forfeited, any dividend equivalents with respect to the underlying award will also fail to become payable and will be forfeited.

Stock options exercised totaled 169,024 for the nine months ended September 30, 2017, 484,829 for the nine months ended September 30, 2016, and 586,132 for the year ended December 31, 2016.

As of September 30, 2017, the Company had 385,549 options, 331,017 RSUs, and 252,290 PSUs (based on target number awarded) outstanding.

Earnings Per Share

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Earnings Per Share

Basic earnings per share excludes dilution and is computed by dividing income applicable to stockholders by the weighted average number of shares outstanding for the period. Diluted earnings per share reflects the potential dilutive impact of all convertible securities on earnings per share. Diluted earnings per share includes shares that are assumed to be issued under the “treasury stock method,” which reflects the potential dilution that would occur if outstanding RSUs and PSUs had vested and options were to be exercised.

Commencing in 2017, certain stock-based compensation awards are eligible to receive dividend equivalents on awards that fully vest or become payable. These awards are not considered participating securities for the purposes of determining earnings per share.

The following table presents the net income and the weighted average number of shares outstanding used in the earnings per common share calculations.



	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2017		2016		2017		2016
	(in millions, except share data)
Net income available to stockholders—basic and diluted	$	21.9	$	22.6	$	69.9	$	71.2
Weighted average number of shares outstanding—basic	32,563,800		32,449,617		32,454,443		32,497,478
Effect of dilutive securities:
PSUs	243,470		238,633		262,992		196,898
Stock options	180,421		192,827		212,044		251,068
RSUs	66,294		67,885		77,738		70,429
Dilutive potential shares	490,185		499,345		552,774		518,395
Weighted average number of shares outstanding—diluted	33,053,985		32,948,962		33,007,217		33,015,873

Diluted earnings per share excludes outstanding options and other common stock equivalents in periods where the inclusion of such options and common stock equivalents would be anti-dilutive. The following table presents options that were excluded from diluted earnings per share.



	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2017	2016	2017	2016
Options excluded under the treasury method as the potential proceeds on settlement or exercise price were greater than the value of shares acquired	—	67,431	—	98,021

Fair Value of Financial Instruments (Tables)

9 Months Ended

Sep. 30, 2017

Fair Value of Financial Instruments [Abstract]

Estimated fair value of financial instruments table

The carrying value and the estimated fair value of the Company’s financial instruments were as follows:



	September 30, 2017				December 31, 2016
	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value
	(in millions)
Financial assets
Investments	$	2,624.8	$	2,624.8	$	2,552.6	$	2,552.6
Cash and cash equivalents	69.4		69.4		67.2		67.2
Restricted cash and cash equivalents	1.1		1.1		3.6		3.6
Financial liabilities
Notes payable	$	20.0	$	23.0	$	32.0	$	33.0

Fair value, assets and liabilities measured on recurring basis table

The following table presents the items in the Company's Consolidated Balance Sheets that are stated at fair value and the corresponding fair value measurements.



	September 30, 2017						December 31, 2016
	Level 1		Level 2		Level 3		Level 1		Level 2		Level 3
	(in millions)
Fixed maturity securities
U.S. Treasuries	$	—	$	132.6	$	—	$	—	$	127.4	$	—
U.S. Agencies	—		13.4		—		—		12.8		—
States and municipalities	—		700.4		—		—		851.6		—
Corporate securities	—		1,060.3		—		—		956.7		—
Residential mortgage-backed securities	—		363.2		—		—		258.0		—
Commercial mortgage-backed securities	—		91.6		—		—		95.5		—
Asset-backed securities	—		54.6		—		—		35.4		7.0
Total fixed maturity securities	$	—	$	2,416.1	$	—	$	—	$	2,337.4	$	7.0
Equity securities
Industrial and miscellaneous	$	175.6	$	—	$	—	$	167.2	$	—	$	—
Non-redeemable preferred (FHLB stock)	—		—		4.7		—		—		4.9
Other	22.9		—		—		20.1		—		—
Total equity securities	$	198.5	$	—	$	4.7	$	187.3	$	—	$	4.9
Short-term investments	$	—	$	5.5	$	—	$	—	$	16.0	$	—

Schedule of Cash and Cash Equivalents [Table Text Block]

The following table presents cash equivalents at NAV and total cash and cash equivalents carried at fair value on the Company's Consolidated Balance Sheets.



	September 30, 2017		December 31, 2016
	(in millions)
Cash and cash equivalents at fair value	$	30.4	$	9.7
Cash equivalents measured at NAV, which approximates fair value	39.0		57.5
Total cash and cash equivalents	$	69.4	$	67.2

Fair value, assets measured on recurring basis, unobservable input reconciliation table

The following table provides a reconciliation of the beginning and ending balances that are measured using Level 3 inputs for the nine months ended September 30, 2017 and 2016.



	Level 3 Securities
	2017			2016
	(in millions)
Beginning balance, January 1	$	11.9		$	—
Transfers (out) of Level 3 ⁽¹⁾	(7.0		)	—
Purchases and sales, net	(0.2		)	4.9
Ending balance, September 30	$	4.7		$	4.9


(1)	Transferred from Level 3 to Level 2 because observable market data became available for the securities.

- Definition

Tabular disclosure of financial instruments measured at fair value, including those classified in shareholders' equity measured on a recurring or nonrecurring basis. Disclosures include, but are not limited to, fair value measurements recorded and the reasons for the measurements, level within the fair value hierarchy in which the fair value measurements are categorized and transfers between levels 1 and 2. Nonrecurring fair value measurements are those that are required or permitted in the statement of financial position in particular circumstances.

+ References + Details

Investments (Tables)

9 Months Ended

Sep. 30, 2017

Investments [Abstract]

Available-for-sale securities table

The cost or amortized cost, gross unrealized gains, gross unrealized losses, and estimated fair value of the Company’s investments were as follows:



	Cost or Amortized Cost		Gross Unrealized Gains		Gross Unrealized Losses			Estimated Fair Value
	(in millions)
At September 30, 2017
Fixed maturity securities
U.S. Treasuries	$	130.3	$	2.5	$	(0.2	)	$	132.6
U.S. Agencies	12.8		0.6		—			13.4
States and municipalities	671.0		30.7		(1.3		)	700.4
Corporate securities	1,040.3		22.0		(2.0		)	1,060.3
Residential mortgage-backed securities	360.1		4.8		(1.7		)	363.2
Commercial mortgage-backed securities	91.7		0.5		(0.6		)	91.6
Asset-backed securities	54.4		0.3		(0.1		)	54.6
Total fixed maturity securities	2,360.6		61.4		(5.9		)	2,416.1
Equity securities
Industrial and miscellaneous	102.8		76.4		(3.6		)	175.6
Non-redeemable preferred (FHLB stock)	4.7		—		—			4.7
Other	11.8		11.1		—			22.9
Total equity securities	119.3		87.5		(3.6		)	203.2
Short-term investments	5.5		—		—			5.5
Total investments	$	2,485.4	$	148.9	$	(9.5	)	$	2,624.8



At December 31, 2016
Fixed maturity securities
U.S. Treasuries	$	124.1	$	3.5	$	(0.2	)	$	127.4
U.S. Agencies	11.9		0.9		—			12.8
States and municipalities	833.0		24.7		(6.1		)	851.6
Corporate securities	942.3		18.9		(4.5		)	956.7
Residential mortgage-backed securities	255.9		4.7		(2.6		)	258.0
Commercial mortgage-backed securities	96.1		0.4		(1.0		)	95.5
Asset-backed securities	42.6		—		(0.2		)	42.4
Total fixed maturity securities	2,305.9		53.1		(14.6		)	2,344.4
Equity securities
Industrial and miscellaneous	100.5		67.4		(0.7		)	167.2
Non-redeemable preferred (FHLB stock)	4.9		—		—			4.9
Other	10.7		9.4		—			20.1
Total equity securities	116.1		76.8		(0.7		)	192.2
Short-term investments	16.0		—		—			16.0
Total investments	$	2,438.0	$	129.9	$	(15.3	)	$	2,552.6

Investments classified by contractual maturity date table



	Amortized Cost		Estimated Fair Value
	(in millions)
Due in one year or less	$	260.8	$	262.2
Due after one year through five years	715.3		737.1
Due after five years through ten years	692.5		713.7
Due after ten years	185.8		193.7
Mortgage and asset-backed securities	506.2		509.4
Total	$	2,360.6	$	2,416.1

Unrealized loss on investments table



	September 30, 2017						December 31, 2016
	Estimated Fair Value		Gross Unrealized Losses			Number of Issues	Estimated Fair Value		Gross Unrealized Losses			Number of Issues
	(in millions, except number of issues data)
Less than 12 months:
Fixed maturity securities
U.S. Treasuries	$	64.7	$	(0.1	)	25	$	33.3	$	(0.2	)	14
States and municipalities	38.9		(0.5		)	10	200.9		(6.1		)	50
Corporate securities	211.9		(1.6		)	72	289.5		(4.1		)	101
Residential mortgage-backed securities	165.1		(1.6		)	52	137.5		(2.6		)	51
Commercial mortgage-backed securities	35.6		(0.4		)	13	48.0		(1.0		)	21
Asset-backed securities	26.7		(0.1		)	25	30.1		(0.2		)	20
Total fixed maturity securities	542.9		(4.3		)	197	739.3		(14.2		)	257
Equity securities	17.5		(3.2		)	30	13.6		(0.6		)	28
Total less than 12 months	$	560.4	$	(7.5	)	227	$	752.9	$	(14.8	)	285

12 months or greater:
Fixed maturity securities
U.S. Treasuries	$	2.9	$	(0.1	)	1	$	—	$	—		—
States and municipalities	21.0		(0.8		)	8	—		—			—
Corporate securities	23.5		(0.4		)	10	15.2		(0.4		)	5
Residential mortgage-backed securities	3.5		(0.1		)	3	—		—			—
Commercial mortgage-backed securities	6.3		(0.2		)	4	—		—			—
Total fixed maturity securities	57.2		(1.6		)	26	15.2		(0.4		)	5
Equity securities	4.0		(0.4		)	2	1.7		(0.1		)	5
Total 12 months or greater	$	61.2	$	(2.0	)	28	$	16.9	$	(0.5	)	10

Total available-for-sale:
Fixed maturity securities
U.S. Treasuries	$	67.6	$	(0.2	)	26	$	33.3	$	(0.2	)	14
States and municipalities	59.9		(1.3		)	18	200.9		(6.1		)	50
Corporate securities	235.4		(2.0		)	82	304.7		(4.5		)	106
Residential mortgage-backed securities	168.6		(1.7		)	55	137.5		(2.6		)	51
Commercial mortgage-backed securities	41.9		(0.6		)	17	48.0		(1.0		)	21
Asset-backed securities	26.7		(0.1		)	25	30.1		(0.2		)	20
Total fixed maturity securities	600.1		(5.9		)	223	754.5		(14.6		)	262
Equity securities	21.5		(3.6		)	32	15.3		(0.7		)	33
Total available-for-sale	$	621.6	$	(9.5	)	255	$	769.8	$	(15.3	)	295

Net realized gains and change in unrealized gains (losses), available for sale securities table

ealized gains on investments and the change in unrealized gains (losses) on fixed maturity and equity securities are determined on a specific-identification basis and were as follows:



	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2017			2016			2017			2016
	(in millions)
Net realized gains on investments
Fixed maturity securities
Gross gains	$	3.5		$	—		$	4.0		$	1.3
Gross losses	(0.7		)	—			(0.8		)	(0.5		)
Net realized gains on fixed maturity securities	$	2.8		$	—		$	3.2		$	0.8
Equity securities
Gross gains	$	1.3		$	1.6		$	4.4		$	14.3
Gross losses	—			—			(0.2		)	(6.0		)
Net realized gains on equity securities	$	1.3		$	1.6		$	4.2		$	8.3
Total	$	4.1		$	1.6		$	7.4		$	9.1

Change in net unrealized gains
Fixed maturity securities	$	(1.9	)	$	(10.2	)	$	17.0		$	43.4
Equity securities	2.4			2.1			7.8			8.9
Total	$	0.5		$	(8.1	)	$	24.8		$	52.3

Investment income table

Net investment income was as follows:



	Three Months Ended						Nine Months Ended
	September 30,						September 30,
	2017			2016			2017			2016
	(in millions)
Fixed maturity securities	$	17.4		$	16.9		$	52.4		$	50.8
Equity securities	1.7			1.7			5.2			5.4
Cash equivalents and restricted cash	0.2			0.1			0.4			0.2
Gross investment income	19.3			18.7			58.0			56.4
Investment expenses	(0.8		)	(0.8		)	(2.6		)	(2.3		)
Net investment income	$	18.5		$	17.9		$	55.4		$	54.1

- Definition

Tabular disclosure of available-for-sale securities which includes, but is not limited to, changes in the cost basis and fair value, fair value and gross unrealized gain (loss), fair values by type of security, contractual maturity and classification, amortized cost basis, contracts to acquire securities to be accounted for as available-for-sale, debt maturities, transfers to trading, change in net unrealized holding gain (loss) net of tax, continuous unrealized loss position fair value, aggregate losses qualitative disclosures, other than temporary impairment (OTTI) losses or other disclosures related to available for sale securities.

+ References + Details

Property and Equipment (Tables)

9 Months Ended

Sep. 30, 2017

Property and Equipment [Abstract]

Property, plant and equipment table

Property and equipment consists of the following:



	As of September 30,			As of December 31,
	2017			2016
	(in millions)
Furniture and equipment	$	1.7		$	2.3
Leasehold improvements	2.9			4.3
Computers and software	54.5			59.0
Automobiles	1.2			1.2
Property and equipment, gross	60.3			66.8
Accumulated depreciation	(45.3		)	(44.6		)
Property and equipment, net	$	15.0		$	22.2

Liability for Unpaid Losses and Loss Adjustment Expenses (Tables)

9 Months Ended

Sep. 30, 2017

Liability for Unpaid Losses and Loss Adjustment Expenses [Abstract]

Changes in the liability for unpaid losses and LAE table

The following table represents a reconciliation of changes in the liability for unpaid losses and LAE.



	Three Months Ended					Nine Months Ended
	September 30,					September 30,
	2017			2016		2017			2016
	(in millions)
Unpaid losses and LAE, gross of reinsurance, at beginning of period	$	2,284.9		$	2,332.3	$	2,301.0		$	2,347.5
Less reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE	559.8			598.8		580.0			628.2
Net unpaid losses and LAE at beginning of period	1,725.1			1,733.5		1,721.0			1,719.3
Losses and LAE, net of reinsurance, incurred during the period related to:
Current period	119.7			111.1		341.0			343.1
Prior periods	(0.2		)	0.8		(0.5		)	(1.5		)
Total net losses and LAE incurred during the period	119.5			111.9		340.5			341.6
Paid losses and LAE, net of reinsurance, related to:
Current period	23.5			23.7		45.2			42.8
Prior periods	75.3			83.2		270.5			279.6
Total net paid losses and LAE during the period	98.8			106.9		315.7			322.4
Ending unpaid losses and LAE, net of reinsurance	1,745.8			1,738.5		1,745.8			1,738.5
Reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE	553.1			591.5		553.1			591.5
Unpaid losses and LAE, gross of reinsurance, at end of period	$	2,298.9		$	2,330.0	$	2,298.9		$	2,330.0

Notes Payable (Tables)

9 Months Ended

Sep. 30, 2017

Notes Payable [Abstract]

Schedule of long-term debt instruments table

Notes payable is comprised of the following:



	September 30, 2017		December 31, 2016
	(in millions)
Dekania Surplus Note, due April 30, 2034	$	10.0	$	10.0
Alesco Surplus Note, due December 15, 2034	10.0		10.0
ICONS Surplus Note, due May 26, 2034	—		12.0
Balance	$	20.0	$	32.0

- Definition

Tabular disclosure of long-debt instruments or arrangements, including identification, terms, features, collateral requirements and other information necessary to a fair presentation. These are debt arrangements that originally required repayment more than twelve months after issuance or greater than the normal operating cycle of the entity, if longer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22)
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21475-112644

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 470
-Section 50
-Paragraph 3
-URI http://asc.fasb.org/extlink&oid=75038535&loc=d3e64711-112823

Reference 4: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 235
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.4-08.(e),(f))
-URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690

Reference 5: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 55
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=64930739&loc=d3e28878-108400

Reference 6: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21538-112644

Reference 7: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 6
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21506-112644

Reference 8: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 1A
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28541-108399

Reference 9: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 835
-SubTopic 30
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=64930785&loc=d3e28551-108399

Reference 10: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 505
-SubTopic 10
-Section 50
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=84159872&loc=d3e21521-112644

+ Details

Stock-Based Compensation Stock-Based Compensation (Tables)

9 Months Ended

Sep. 30, 2017

Stock-Based Compensation [Abstract]

Share-based compensation arrangements by share-based payment award table

The Company awarded restricted stock units (RSUs) and performance share units (PSUs) to certain employees and non-employee Directors of the Company as follows:



	Number Awarded	Weighted Average Fair Value on Date of Grant		Weighted Average Exercise Price		Aggregate Fair Value on Date of Grant
						(in millions)
March 2017
RSUs⁽¹⁾	72,020	$	37.60	$	—	$	2.7
PSUs⁽²⁾	97,440	37.60		—		3.7

May 2017
RSUs⁽¹⁾	11,888	$	40.35	$	—	$	0.5

July 2017
RSUs⁽¹⁾	1,251	43.95		$	—	$	0.1


(1)	The RSUs awarded in March 2017 were awarded to certain employees of the Company and vest 25% on March 15, 2018, and each of the subsequent three anniversaries of that date. The RSUs are subject to accelerated vesting in certain circumstances, including but not limited to: death, disability, retirement, or in connection with change of control of the Company.

The RSUs awarded in May 2017 and July 2017 were awarded to non-employee Directors of the Company and vest on May 25, 2018.


(2)	The PSUs awarded in March 2017 were awarded to certain employees of the Company and have a performance period of two years followed by an additional one year vesting period. The PSU awards are subject to certain performance goals with payouts that range from 0% to 200% of the target awards. The value shown in the table represents the aggregate number of PSUs awarded at the target level.

Earnings Per Share (Tables)

9 Months Ended

Sep. 30, 2017

Earnings Per Share [Abstract]

Net income and weighted average common shares outstanding used in earnings per share calculations table

The following table presents the net income and the weighted average number of shares outstanding used in the earnings per common share calculations.



	Three Months Ended				Nine Months Ended
	September 30,				September 30,
	2017		2016		2017		2016
	(in millions, except share data)
Net income available to stockholders—basic and diluted	$	21.9	$	22.6	$	69.9	$	71.2
Weighted average number of shares outstanding—basic	32,563,800		32,449,617		32,454,443		32,497,478
Effect of dilutive securities:
PSUs	243,470		238,633		262,992		196,898
Stock options	180,421		192,827		212,044		251,068
RSUs	66,294		67,885		77,738		70,429
Dilutive potential shares	490,185		499,345		552,774		518,395
Weighted average number of shares outstanding—diluted	33,053,985		32,948,962		33,007,217		33,015,873

Antidilutive securities excluded from computation of earnings per share table

The following table presents options that were excluded from diluted earnings per share.



	Three Months Ended		Nine Months Ended
	September 30,		September 30,
	2017	2016	2017	2016
Options excluded under the treasury method as the potential proceeds on settlement or exercise price were greater than the value of shares acquired	—	67,431	—	98,021

Fair Value of Financial Instruments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016	Sep. 30, 2016	Dec. 31, 2015
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	$ 2,624,800	$ 2,552,600
Investments, estimated fair value	2,624,800	2,552,600
Cash and cash equivalents	69,400	67,200	$ 84,100	$ 56,600
Cash and cash equivalents, estimated fair value	69,400	67,200
Restricted cash and cash equivalents	1,100	3,600
Notes payable	20,000	32,000
Notes Payable, estimated fair value	23,000	33,000
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Restricted cash and cash equivalents	$ 1,100	$ 3,600

- Definition

Fair value portion of investment securities, including, but not limited to, marketable securities, derivative financial instruments, and investments accounted for under the equity method.

+ References + Details

Fair Value of Financial Instruments Cash Equivalents at NAV and Total Cash and Cash Equivalents Carried at Fair Value (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Cash and Cash Equivalents [Line Items]
Cash and cash equivalents at fair value	$ 30.4	$ 9.7
Cash equivalents measured at NAV, which approximates fair value	39.0	57.5
Total cash and cash equivalents	$ 69.4	$ 67.2

Fair Value of Financial Instruments Fair Value of Financial Instruments, Reconciliation of Level 3 Securities (Details) - USD ($)
$ in Thousands

9 Months Ended

Sep. 30, 2017

Sep. 30, 2016

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]

Beginning balance, January 1

$ 2,552,600

Transfers (out) of Level 3 (1)

(7,000)

^[1]

$ 0

Purchases and sales, net

(200)

4,900

Ending balance, September 30

2,624,800

Fair Value, Inputs, Level 3 [Member]

Fair Value, Assets Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items]

Beginning balance, January 1

11,900

Ending balance, September 30

$ 4,700

$ 4,900

[1]	(1)Transferred from Level 3 to Level 2 because observable market data became available for the securities.

Investments (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 2,485,400	$ 2,438,000
Gross unrealized gain	148,900	129,900
Gross unrealized loss	(9,500)	(15,300)
Investments	2,624,800	2,552,600
Deposit Assets
Investments	2,624,800	2,552,600
Assets Held-in-trust
Investments	2,624,800	2,552,600
Funds Held under Reinsurance Agreements, Asset	25,200	27,200
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	2,360,600	2,305,900
Gross unrealized gain	61,400	53,100
Gross unrealized loss	(5,900)	(14,600)
Investments	2,416,100	2,344,400
Deposit Assets
Investments	2,416,100	2,344,400
Assets Held-in-trust
Investments	2,416,100	2,344,400
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	130,300	124,100
Gross unrealized gain	2,500	3,500
Gross unrealized loss	(200)	(200)
Investments	132,600	127,400
Deposit Assets
Investments	132,600	127,400
Assets Held-in-trust
Investments	132,600	127,400
US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	12,800	11,900
Gross unrealized gain	600	900
Gross unrealized loss	0	0
Investments	13,400	12,800
Deposit Assets
Investments	13,400	12,800
Assets Held-in-trust
Investments	13,400	12,800
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	671,000	833,000
Gross unrealized gain	30,700	24,700
Gross unrealized loss	(1,300)	(6,100)
Investments	700,400	851,600
Deposit Assets
Investments	700,400	851,600
Assets Held-in-trust
Investments	700,400	851,600
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	1,040,300	942,300
Gross unrealized gain	22,000	18,900
Gross unrealized loss	(2,000)	(4,500)
Investments	1,060,300	956,700
Deposit Assets
Investments	1,060,300	956,700
Assets Held-in-trust
Investments	1,060,300	956,700
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	360,100	255,900
Gross unrealized gain	4,800	4,700
Gross unrealized loss	(1,700)	(2,600)
Investments	363,200	258,000
Deposit Assets
Investments	363,200	258,000
Assets Held-in-trust
Investments	363,200	258,000
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	91,700	96,100
Gross unrealized gain	500	400
Gross unrealized loss	(600)	(1,000)
Investments	91,600	95,500
Deposit Assets
Investments	91,600	95,500
Assets Held-in-trust
Investments	91,600	95,500
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	54,400	42,600
Gross unrealized gain	300	0
Gross unrealized loss	(100)	(200)
Investments	54,600	42,400
Deposit Assets
Investments	54,600	42,400
Assets Held-in-trust
Investments	54,600	42,400
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	119,300	116,100
Gross unrealized gain	87,500	76,800
Gross unrealized loss	(3,600)	(700)
Investments	203,200	192,200
Deposit Assets
Investments	203,200	192,200
Assets Held-in-trust
Investments	203,200	192,200
Industrial and Miscellaneous [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	102,800	100,500
Gross unrealized gain	76,400	67,400
Gross unrealized loss	(3,600)	(700)
Investments	175,600	167,200
Deposit Assets
Investments	175,600	167,200
Assets Held-in-trust
Investments	175,600	167,200
Non-redeemable preferred (FHLB stock) [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	4,700	4,900
Gross unrealized gain	0	0
Gross unrealized loss	0	0
Investments	4,700	4,900
Deposit Assets
Investments	4,700	4,900
Assets Held-in-trust
Investments	4,700	4,900
Other [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	11,800	10,700
Gross unrealized gain	11,100	9,400
Gross unrealized loss	0	0
Investments	22,900	20,100
Deposit Assets
Investments	22,900	20,100
Assets Held-in-trust
Investments	22,900	20,100
Short-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	5,500	16,000
Gross unrealized gain	0	0
Gross unrealized loss	0	0
Investments	5,500	16,000
Deposit Assets
Investments	5,500	16,000
Assets Held-in-trust
Investments	5,500	16,000
Required by various state laws and regulations to hold securities or letters of credit in depository account [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments	1,017,700	1,009,700
Deposit Assets
Investments	1,017,700	1,009,700
Assets Held-in-trust
Investments	$ 1,017,700	$ 1,009,700

Investments, Amortized Cost and Estimated Fair Value (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Amortized Cost
Due in one year or less, amortized cost	$ 260,800
Due after one year through five years, amortized cost	715,300
Due after five years through ten years, amortized cost	692,500
Due after ten years, amortized cost	185,800
Mortgage and asset-backed securities, amortized cost	506,200
Total, amortized cost	2,360,600
Estimated Fair Value
Due in one year or less, fair value	262,200
Due after one year through five years, fair value	737,100
Due after five years through ten years, fair value	713,700
Due after ten years, fair value	193,700
Mortgage and asset-backed securities, fair value	509,400
Total, fair value	$ 2,416,100	$ 2,344,400

Investments, Continuous Loss Position (Details)	3 Months Ended		9 Months Ended
Investments, Continuous Loss Position (Details)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Sep. 30, 2017 USD ($)	Sep. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Estimated Fair Value
Estimated fair value, less than 12 months	$ 560,400,000		$ 560,400,000		$ 752,900,000
Estimated fair value, 12 months or greater	61,200,000		61,200,000		16,900,000
Estimated fair value, total	621,600,000		621,600,000		769,800,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(7,500,000)		(7,500,000)		(14,800,000)
Gross unrealized losses, 12 months or greater	2,000,000		2,000,000		500,000
Estimated unrealized losses, total	$ (9,500,000)		$ (9,500,000)		$ (15,300,000)
Number of issues in loss position, less than 12 months	227		227		285
Number of Issues in loss position, 12 months or greater	28		28		10
Number of issues loss position, aggregate	255		255		295
Other than temporary impairment, credit losses recognized in earnings	$ 0	$ 0	$ 200,000	$ 5,300,000
Total impairments, number of securities	1		1
Debt Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 542,900,000		$ 542,900,000		$ 739,300,000
Estimated fair value, 12 months or greater	57,200,000		57,200,000		15,200,000
Estimated fair value, total	600,100,000		600,100,000		754,500,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(4,300,000)		(4,300,000)		(14,200,000)
Gross unrealized losses, 12 months or greater	1,600,000		1,600,000		400,000
Estimated unrealized losses, total	$ (5,900,000)		$ (5,900,000)		$ (14,600,000)
Number of issues in loss position, less than 12 months	197		197		257
Number of Issues in loss position, 12 months or greater	26		26		5
Number of issues loss position, aggregate	223		223		262
US Treasury Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 64,700,000		$ 64,700,000		$ 33,300,000
Estimated fair value, 12 months or greater	2,900,000		2,900,000		0
Estimated fair value, total	67,600,000		67,600,000		33,300,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(100,000)		(100,000)		(200,000)
Gross unrealized losses, 12 months or greater	100,000		100,000		0
Estimated unrealized losses, total	$ (200,000)		$ (200,000)		$ (200,000)
Number of issues in loss position, less than 12 months	25		25		14
Number of Issues in loss position, 12 months or greater	1		1		0
Number of issues loss position, aggregate	26		26		14
US Government Agencies Debt Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 0		$ 0		$ 0
Estimated fair value, total	0		0		0
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	0		0		0
Estimated unrealized losses, total	$ 0		$ 0		$ 0
Number of issues in loss position, less than 12 months	0		0		0
Number of issues loss position, aggregate	0		0		0
US States and Political Subdivisions Debt Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 38,900,000		$ 38,900,000		$ 200,900,000
Estimated fair value, 12 months or greater	21,000,000		21,000,000		0
Estimated fair value, total	59,900,000		59,900,000		200,900,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(500,000)		(500,000)		(6,100,000)
Gross unrealized losses, 12 months or greater	800,000		800,000		0
Estimated unrealized losses, total	$ (1,300,000)		$ (1,300,000)		$ (6,100,000)
Number of issues in loss position, less than 12 months	10		10		50
Number of Issues in loss position, 12 months or greater	8		8		0
Number of issues loss position, aggregate	18		18		50
Corporate Debt Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 211,900,000		$ 211,900,000		$ 289,500,000
Estimated fair value, 12 months or greater	23,500,000		23,500,000		15,200,000
Estimated fair value, total	235,400,000		235,400,000		304,700,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(1,600,000)		(1,600,000)		(4,100,000)
Gross unrealized losses, 12 months or greater	400,000		400,000		400,000
Estimated unrealized losses, total	$ (2,000,000)		$ (2,000,000)		$ (4,500,000)
Number of issues in loss position, less than 12 months	72		72		101
Number of Issues in loss position, 12 months or greater	10		10		5
Number of issues loss position, aggregate	82		82		106
Residential Mortgage Backed Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 165,100,000		$ 165,100,000		$ 137,500,000
Estimated fair value, 12 months or greater	3,500,000		3,500,000		0
Estimated fair value, total	168,600,000		168,600,000		137,500,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(1,600,000)		(1,600,000)		(2,600,000)
Gross unrealized losses, 12 months or greater	100,000		100,000		0
Estimated unrealized losses, total	$ (1,700,000)		$ (1,700,000)		$ (2,600,000)
Number of issues in loss position, less than 12 months	52		52		51
Number of Issues in loss position, 12 months or greater	3		3		0
Number of issues loss position, aggregate	55		55		51
Commercial Mortgage Backed Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 35,600,000		$ 35,600,000		$ 48,000,000
Estimated fair value, 12 months or greater	6,300,000		6,300,000		0
Estimated fair value, total	41,900,000		41,900,000		48,000,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(400,000)		(400,000)		(1,000,000)
Gross unrealized losses, 12 months or greater	200,000		200,000		0
Estimated unrealized losses, total	$ (600,000)		$ (600,000)		$ (1,000,000)
Number of issues in loss position, less than 12 months	13		13		21
Number of Issues in loss position, 12 months or greater	4		4		0
Number of issues loss position, aggregate	17		17		21
Asset-backed Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 26,700,000		$ 26,700,000		$ 30,100,000
Estimated fair value, total	26,700,000		26,700,000		30,100,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(100,000)		(100,000)		(200,000)
Estimated unrealized losses, total	$ (100,000)		$ (100,000)		$ (200,000)
Number of issues in loss position, less than 12 months	0		0		0
Number of issues loss position, aggregate	0		0		0
Equity Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	$ 17,500,000		$ 17,500,000		$ 13,600,000
Estimated fair value, 12 months or greater	4,000,000		4,000,000		1,700,000
Estimated fair value, total	21,500,000		21,500,000		15,300,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(3,200,000)		(3,200,000)		(600,000)
Gross unrealized losses, 12 months or greater	400,000		400,000		100,000
Estimated unrealized losses, total	$ (3,600,000)		$ (3,600,000)		$ (700,000)
Number of issues in loss position, less than 12 months	30		30		28
Number of Issues in loss position, 12 months or greater	2		2		5
Number of issues loss position, aggregate	32		32		33

Investments, Net Realized Gains (Losses) (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Net realized gains (losses)
Net realized gains (losses) on fixed maturity and equity securities	$ 4.1	$ 1.6	$ 7.4	$ 9.1
Change in unrealized gains (losses)
Change in unrealized gains (losses) on fixed maturity and equity securities	0.5	(8.1)	24.8	52.3
Debt Securities [Member]
Net realized gains (losses)
Gross gains from sales	3.5	0.0	4.0	1.3
Gross losses from sales	0.7	0.0	0.8	0.5
Net realized gains (losses) on fixed maturity and equity securities	2.8	0.0	3.2	0.8
Change in unrealized gains (losses)
Change in unrealized gains (losses) on fixed maturity and equity securities	(1.9)	(10.2)	17.0	43.4
Equity Securities [Member]
Net realized gains (losses)
Gross gains from sales	1.3	1.6	4.4	14.3
Gross losses from sales	0.0	0.0	0.2	6.0
Net realized gains (losses) on fixed maturity and equity securities	1.3	1.6	4.2	8.3
Change in unrealized gains (losses)
Change in unrealized gains (losses) on fixed maturity and equity securities	$ 2.4	$ 2.1	$ 7.8	$ 8.9

Net Investment Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
Net Investment Income (Details) - USD ($) $ in Millions	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	$ 19.3	$ 18.7	$ 58.0	$ 56.4
Investment expenses	0.8	0.8	2.6	2.3
Net investment income	18.5	17.9	55.4	54.1
Debt Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income related to fixed maturity securities and short-term investments and cash equivalents	17.4	16.9	52.4	50.8
Equity Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income related to equity securities	1.7	1.7	5.2	5.4
Short-term Investments [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income related to fixed maturity securities and short-term investments and cash equivalents	$ 0.2	$ 0.1	$ 0.4	$ 0.2

Property and Equipment Property and Equipment breakout (Details) - USD ($) $ in Thousands	3 Months Ended	9 Months Ended	12 Months Ended
	Sep. 30, 2017	Sep. 30, 2017	Dec. 31, 2016
Property and Equipment [Line Items]
Property and equipment, gross	$ 60,300	$ 60,300	$ 66,800
Accumulated depreciation, depletion and amortization, property, and equipment	(45,300)	(45,300)	(44,600)
Property and equipment, net	15,000	15,000	22,200
Utilities operating expense, depreciation and amortization		6,000	8,200
Payments to develop software		1,800	1,300
Asset impairment charges	7,500
Furniture and equipment
Property and Equipment [Line Items]
Property and equipment, gross	1,700	1,700	2,300
Leasehold improvements
Property and Equipment [Line Items]
Property and equipment, gross	2,900	2,900	4,300
Computers and software
Property and Equipment [Line Items]
Property and equipment, gross	54,500	54,500	59,000
Automobiles
Property and Equipment [Line Items]
Property and equipment, gross	$ 1,200	$ 1,200	$ 1,200

Income Taxes (Details)	9 Months Ended
Income Taxes (Details)	Sep. 30, 2017	Sep. 30, 2016
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Statutory tax rate	35.00%
Effective tax rate	23.20%	22.90%

Liability for Unpaid Losses and Loss Adjustment Expenses (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Unpaid losses and LAE, gross of reinsurance, at beginning of period	$ 2,284,900	$ 2,332,300	$ 2,301,000	$ 2,347,500
Less reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE	559,800	598,800	580,000	628,200
Net unpaid losses and LAE at beginning of period	1,725,100	1,733,500	1,721,000	1,719,300
Losses and LAE, net of reinsurance, incurred during the period related to:
Current period	119,700	111,100	341,000	343,100
Prior periods	(200)	800	(500)	(1,500)
Total net losses and LAE incurred during the period	119,500	111,900	340,500	341,600
Deduct payments for losses and LAE, net of reinsurance, related to:
Current period	23,500	23,700	45,200	42,800
Prior periods	75,300	83,200	270,500	279,600
Total net paid losses and LAE during the period	98,800	106,900	315,700	322,400
Ending unpaid losses and LAE, net of reinsurance	1,745,800	1,738,500	1,745,800	1,738,500
Reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE	553,100	591,500	553,100	591,500
Unpaid losses and LAE, gross of reinsurance, at end of period	2,298,900	2,330,000	2,298,900	2,330,000
LPT Agreement [Abstract]
Impact of the LPT Agreement	$ 2,500	$ 3,000	$ 8,500	$ 13,600

LPT Agreement LPT Agreement (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Reinsurance Agreement [Line Items]
Liabilities for the incurred but unpaid losses and LAE related to claims prior to July 1, 1995	$ 1,500,000		$ 1,500,000
Ceded premiums written			775,000
Amortization of deferred gain	2,500	$ 3,000	8,500	$ 8,700
LPT reserve adjustment				3,100
LPT contingent commission adjustment				$ 1,800
Deferred reinsurance gain—LPT Agreement	166,400		166,400		$ 174,900
Estimated remaining liabilities - LPT Agreement	445,400		445,400		465,500
Paid losses and LAE claims related to LPT	742,700		742,700		$ 722,700
Indemnification Agreement [Member]
Reinsurance Agreement [Line Items]
Coverage provided under LPT Agreement	$ 2,000,000		$ 2,000,000

Notes Payable Notes Payable Outstanding(Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016	Dec. 31, 2016
Debt Instrument [Line Items]
Notes payable	$ 20,000		$ 20,000		$ 32,000
Gain on redemption of notes payable	0	$ 0	2,100	$ 0
Redemption of notes payable			9,900	$ 0
Dekania Surplus Note [Member]
Debt Instrument [Line Items]
Notes payable	10,000		$ 10,000		10,000
Notes payable, maturity date			Apr. 30, 2034
Notes payable, callable			2009
Interest rate, basis points in excess of the 90-day LIBOR			425
ICONS Surplus Note [Member]
Debt Instrument [Line Items]
Notes payable	0		$ 0		12,000
Date notes payable was redeemed			May 01, 2017
Gain on redemption of notes payable			$ 2,100
Redemption of notes payable			9,900
Alesco Surplus Note [Member]
Debt Instrument [Line Items]
Notes payable	$ 10,000		$ 10,000		$ 10,000
Notes payable, maturity date			Dec. 15, 2034
Notes payable, callable			2009
Interest rate, basis points in excess of the 90-day LIBOR			405

Accumulated Other Comprehensive Income (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Dec. 31, 2016
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net unrealized gain on investments, before taxes	$ 139,400	$ 114,600
Deferred tax expense on net unrealized gains	(48,800)	(40,100)
Accumulated other comprehensive income, net	$ 90,600	$ 74,500

Stock-Based Compensation (Details) - USD ($)
$ / shares in Units, $ in Millions

1 Months Ended

3 Months Ended

9 Months Ended

12 Months Ended

Jul. 31, 2017

May 31, 2017

Mar. 31, 2017

Sep. 30, 2017

Sep. 30, 2016

Dec. 31, 2016

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Stock-options exercised

169,024

484,829

586,132

Officer [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vesting rights for RSUs awarded

vest 25% on March 15, 2018, and each of the subsequent three anniversaries of that date

Performance share awards performance period

two years

Performance share awards, minimum payout

0.00%

Performance share awards, maximum payout

200.00%

Director [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Vesting rights for RSUs awarded

vest on May 25, 2018

Stock Option [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Number of outstanding options or share units

385,549

Restricted Stock Units (RSUs) [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based compensation award, shares issued

^[1]

1,251

11,888

72,020

Share-based compensation options, exercise price on grant date

^[1]

$ 43.95

$ 40.35

$ 37.60

Share-based compensation award, fair value assumptions, exercise price

$ 0

Fair value of awards awarded on grant date

^[1]

$ 0.1

$ 0.5

$ 2.7

Number of outstanding options or share units

331,017

Performance Shares [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based compensation award, shares issued

^[2]

97,440

Share-based compensation options, exercise price on grant date

^[2]

$ 37.60

Share-based compensation award, fair value assumptions, exercise price

$ 0

Fair value of awards awarded on grant date

^[2]

$ 3.7

Number of outstanding options or share units

252,290

Performance Shares [Member] | Officer [Member]

Share-based Compensation Arrangement by Share-based Payment Award [Line Items]

Share-based compensation arrangement by share-based payment award, award vesting period

1 year

[1]

The RSUs awarded in March 2017 were awarded to certain employees of the Company and vest 25% on March 15, 2018, and each of the subsequent three anniversaries of that date. The RSUs are subject to accelerated vesting in certain circumstances, including but not limited to: death, disability, retirement, or in connection with change of control of the Company.The RSUs awarded in May 2017 and July 2017 were awarded to non-employee Directors of the Company and vest on May 25, 2018.

[2]

The PSUs awarded in March 2017 were awarded to certain employees of the Company and have a performance period of two years followed by an additional one year vesting period. The PSU awards are subject to certain performance goals with payouts that range from 0% to 200% of the target awards. The value shown in the table represents the aggregate number of PSUs awarded at the target level.

Earnings Per Share (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
Earnings Per Share (Details) - USD ($) $ in Thousands	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Net income available to stockholders - basic and diluted	$ 21,900	$ 22,600	$ 69,900	$ 71,200
Weighted average number of shares outstanding - basic	32,563,800	32,449,617	32,454,443	32,497,478
Effect of dilutive securities:
Dilutive securities	490,185	499,345	552,774	518,395
Weighted average number of shares outstanding - diluted	33,053,985	32,948,962	33,007,217	33,015,873
Antidilutive securites excluded under the treasury method from computation of earnings per share	0	67,431	0	98,021
Employee Stock Option [Member]
Effect of dilutive securities:
Dilutive securities	180,421	192,827	212,044	251,068
Restricted Stock Units (RSUs) [Member]
Effect of dilutive securities:
Dilutive securities	66,294	67,885	77,738	70,429
Performance Shares [Member]
Effect of dilutive securities:
Dilutive securities	243,470	238,633	262,992	196,898

Conslidated Stockholders Equity (Parentheticals) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016
Statement of Stockholders' Equity Parenthetical [Abstract]
Change in net unrealized gains on investments, net of tax	$ 8.7	$ 18.3

Basis of Presentation (Details)	9 Months Ended
Basis of Presentation (Details)	Sep. 30, 2017
Basis of Presentation [Abstract]
Number of operating segments	1

Fair Value of Financial Instruments, Fair Value Inputs (Details) - USD ($) $ in Millions	Sep. 30, 2017	Dec. 31, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 2,624.8	$ 2,552.6
Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	2,416.1	2,344.4
Debt Securities [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Debt Securities [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	2,416.1	2,337.4
Debt Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	7.0
US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	132.6	127.4
US Treasury Securities [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
US Treasury Securities [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	132.6	127.4
US Treasury Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
US Government Agencies Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	13.4	12.8
US Government Agencies Debt Securities [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
US Government Agencies Debt Securities [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	13.4	12.8
US Government Agencies Debt Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
US States and Political Subdivisions Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	700.4	851.6
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	700.4	851.6
US States and Political Subdivisions Debt Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	1,060.3	956.7
Corporate Debt Securities [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Corporate Debt Securities [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	1,060.3	956.7
Corporate Debt Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	363.2	258.0
Residential Mortgage Backed Securities [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Residential Mortgage Backed Securities [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	363.2	258.0
Residential Mortgage Backed Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	91.6	95.5
Commercial Mortgage Backed Securities [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Commercial Mortgage Backed Securities [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	91.6	95.5
Commercial Mortgage Backed Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	54.6	42.4
Asset-backed Securities [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Asset-backed Securities [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	54.6	35.4
Asset-backed Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	7.0
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	203.2	192.2
Equity Securities [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	198.5	187.3
Equity Securities [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Equity Securities [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	4.7	4.9
Industrial and Miscellaneous [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	175.6	167.2
Industrial and Miscellaneous [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	175.6	167.2
Industrial and Miscellaneous [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Industrial and Miscellaneous [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Non-redeemable preferred (FHLB stock) [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	4.7	4.9
Non-redeemable preferred (FHLB stock) [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Non-redeemable preferred (FHLB stock) [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Non-redeemable preferred (FHLB stock) [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	4.7	4.9
Other [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	22.9	20.1
Other [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	22.9	20.1
Other [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Other [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Short-term Investments [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	5.5	16.0
Short-term Investments [Member] \| Fair Value, Inputs, Level 1 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	0.0	0.0
Short-term Investments [Member] \| Fair Value, Inputs, Level 2 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments		16.0
Short-term Investments [Member] \| Fair Value, Inputs, Level 3 [Member] \| Fair Value, Measurements, Recurring [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 0.0	$ 0.0