Document and Entity Information	6 Months Ended
Document and Entity Information	Jun. 30, 2015	Jul. 23, 2015
Document and Entity Information [Abstract]
Document Type	10-Q
Amendment Flag	false
Document Period End Date	Jun. 30, 2015
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		32,036,774
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q2

Consolidated Balance Sheets (USD $) In Thousands, unless otherwise specified	Jun. 30, 2015	Dec. 31, 2014
Available for sale:
Fixed maturity securities at fair value (amortized cost $2,211,200 at June 30, 2015 and $2,186,100 at December 31, 2014)	$ 2,281,800	$ 2,275,700
Equity securities at fair value (cost $150,300 at June 30, 2015 and $97,800 at December 31, 2014)	217,300	172,700
Short-term investments at fair value (amortized cost $18,500 at June 30, 2015)	18,500	0
Total investments	2,517,600	2,448,400
Cash and cash equivalents	64,900	103,600
Restricted cash and cash equivalents	6,600	10,800
Accrued investment income	20,600	20,500
Premiums receivable (less bad debt allowance of $10,300 at June 30, 2015 and $7,900 at December 31, 2014)	314,600	295,800
Reinsurance recoverable for:
Paid losses	7,500	10,700
Unpaid losses	640,900	669,500
Deferred policy acquisition costs	48,100	44,600
Deferred income taxes, net	55,400	49,700
Property and equipment, net	23,200	21,000
Intangible assets, net	8,800	9,000
Goodwill	36,200	36,200
Contingent commission receivable—LPT Agreement	29,200	26,400
Other assets	37,800	23,500
Total assets	3,811,400	3,769,700
Claims and policy liabilities:
Unpaid losses and loss adjustment expenses	2,354,500	2,369,700
Unearned premiums	341,400	310,800
Total claims and policy liabilities	2,695,900	2,680,500
Commissions and premium taxes payable	48,800	46,300
Accounts payable and accrued expenses	16,400	20,400
Deferred reinsurance gain—LPT Agreement	195,100	207,000
Notes payable	92,000	92,000
Other liabilities	48,700	36,700
Total liabilities	3,096,900	3,082,900
Commitments and contingencies
Stockholders’ equity:
Common stock, $0.01 par value; 150,000,000 shares authorized; 55,409,748 and 54,866,802 shares issued and 32,036,774 and 31,493,828 shares outstanding at June 30, 2015 and December 31, 2014, respectively	600	600
Preferred stock, $0.01 par value; 25,000,000 shares authorized; none issued	0	0
Additional paid-in capital	352,300	346,600
Retained earnings	634,700	595,300
Accumulated other comprehensive income, net	89,500	106,900
Treasury stock, at cost (23,372,974 shares at June 30, 2015 and December 31, 2014)	(362,600)	(362,600)
Total stockholders’ equity	714,500	686,800
Total liabilities and stockholders’ equity	$ 3,811,400	$ 3,769,700

Consolidated Balance Sheets (Parentheticals) (USD $) In Thousands, except Share data, unless otherwise specified	Jun. 30, 2015	Dec. 31, 2014
Available for sale:
Fixed maturity securities, amortized cost	$ 2,380,000	$ 2,283,900
Available for sale, short-term investments, at amortized cost	18,500	0
Premiums receivable, bad debt allowance	10,300	7,900
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)	55,409,748	54,866,802
Common stock, shares outstanding (in shares)	32,036,774	31,493,828
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)	23,372,974	23,372,974
Debt Securities [Member]
Available for sale:
Fixed maturity securities, amortized cost	2,211,200	2,186,100
Equity Securities [Member]
Available for sale:
Fixed maturity securities, amortized cost	150,300	97,800
Short-term Investments [Member]
Available for sale:
Fixed maturity securities, amortized cost	$ 18,500

Consolidated Statements of Income (USD $) In Thousands, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Revenues
Net premiums earned	$ 170,600	$ 172,600	$ 329,600	$ 339,900
Net investment income	18,400	18,300	35,300	36,300
Net realized gains on investments	1,900	9,200	3,100	12,400
Other income	0	200	100	200
Total revenues	190,900	200,300	368,100	388,800
Expenses
Losses and loss adjustment expenses	101,500	98,500	207,700	220,800
Commission expense	22,900	20,400	41,600	40,400
Underwriting and other operating expenses	32,500	33,100	66,000	66,400
Interest expense	700	700	1,400	1,500
Total expenses	157,600	152,700	316,700	329,100
Net income before income taxes	33,300	47,600	51,400	59,700
Income tax expense	4,100	2,000	8,200	3,300
Net income	29,200	45,600	43,200	56,400
Earnings per common share (Note 11):
Basic	$ 0.91	$ 1.45	$ 1.35	$ 1.79
Diluted	$ 0.90	$ 1.42	$ 1.33	$ 1.76
Cash dividends declared per common share	$ 0.06	$ 0.06	$ 0.12	$ 0.12
Comprehensive income
Unrealized (losses) gains during the period (net of tax (benefit) expense of $(13,300) and $8,600 for the three months ended June 30, 2015 and 2014, respectively, and $(8,300) and $14,100 for the six months ended June 30, 2015 and 2014, respectively)	(24,600)	16,100	(15,400)	26,300
Reclassification adjustment for realized gains in net income (net of taxes of $700 and $3,200 for the three months ended June 30, 2015 and 2014, respectively, and $1,100 and $4,300 for the six months ended June 30, 2015 and 2014, respectively)	(1,200)	(6,000)	(2,000)	(8,100)
Other comprehensive (loss) income, net of tax	(25,800)	10,100	(17,400)	18,200
Total comprehensive income	3,400	55,700	25,800	74,600
Net realized gains on investments
Net realized gains on investments before credit related impairments	2,000	9,200	3,200	12,400
Other than temporary impairment, credit losses recognized in earnings	(100)	0	(100)	0
Net realized gains on investments	$ 1,900	$ 9,200	$ 3,100	$ 12,400

Consolidated Statements of Cash Flows (USD $) In Thousands, unless otherwise specified	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014
Operating activities
Net income	$ 43,200	$ 56,400
Adjustments to reconcile net income to net cash provided by operating activities:
Depreciation and amortization	3,600	3,500
Stock-based compensation	2,700	3,500
Amortization of premium on investments, net	6,100	5,100
Deferred income tax expense	3,700	300
Realized gains on investments, net	(3,100)	(12,400)
Excess tax benefits from stock-based compensation	(700)	(1,200)
Other	2,500	0
Change in operating assets and liabilities:
Premiums receivable	(21,200)	(43,000)
Reinsurance recoverable for paid and unpaid losses	31,800	43,200
Federal income taxes	0	3,300
Unpaid losses and loss adjustment expenses	(15,200)	24,300
Unearned premiums	30,600	35,700
Accounts payable, accrued expenses and other liabilities	8,000	9,000
Deferred reinsurance gain—LPT Agreement	(11,900)	(26,000)
Contingent commission receivable—LPT Agreement	(2,800)	(9,300)
Other	(14,900)	(14,300)
Net cash provided by operating activities	62,400	78,100
Investing activities
Purchase of fixed maturity securities	(256,600)	(215,900)
Purchase of equity securities	(65,700)	(14,200)
Proceeds from sale of fixed maturity securities	50,700	38,000
Proceeds from sale of equity securities	16,300	21,300
Proceeds from maturities and redemptions of investments	156,300	100,700
Capital expenditures	(5,600)	(2,400)
Change in restricted cash and cash equivalents	4,200	(1,900)
Net cash used in investing activities	(100,400)	(74,400)
Financing activities
Cash transactions related to stock-based compensation	2,400	1,400
Dividends paid to stockholders	(3,800)	(3,800)
Excess tax benefits from stock-based compensation, financing activities	700	1,200
Net cash used in financing activities	(700)	(1,200)
Net (decrease) increase in cash and cash equivalents	(38,700)	2,500
Cash and cash equivalents at the beginning of the period	103,600	34,500
Cash and cash equivalents at the end of the period	$ 64,900	$ 37,000

Basis of Presentation	6 Months Ended
Basis of Presentation	Jun. 30, 2015
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. 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 Annual Report on Form 10-K for the year ended December 31, 2014. 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, as well as 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, deferred income taxes, valuation of investments, and the valuation of goodwill and intangible assets.

Changes in Estimates Level 1 (Notes)

6 Months Ended

Jun. 30, 2015

Changes in Estimates [Abstract]

Accounting Changes and Error Corrections

Change in Estimates

During the second quarter of 2015, the Company reduced its estimated reserves ceded under the Loss Portfolio Transfer Agreement (LPT Reserve Adjustment) as a result of the determination that an adjustment was necessary to reflect observed favorable paid loss trends. The following table shows the financial statement impact related to the reduction in estimated reserves ceded under the Loss Portfolio Transfer Agreement (LPT Agreement).



	Three Months Ended			Six Months Ended
	June 30, 2015			June 30, 2015
	(in millions, except per share data)
Change in estimated reserves ceded under the LPT Agreement	$	(10.0	)	$	(10.0	)
Cumulative adjustment to the Deferred Gain⁽¹⁾	(6.4		)	(6.4		)
Net income impact of change in estimate	6.4			6.4
EPS impact of change in estimate
Basic and Diluted	0.20			0.20


(1)	The cumulative adjustment to the Deferred reinsurance gain–LPT Agreement (Deferred Gain) was also recognized in losses and LAE incurred in the Consolidated Statement of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised reserves been recognized at the inception of the LPT Agreement.

During the three months ended June 30, 2015, the Company increased its estimate of contingent commission receivable – LPT Agreement (LPT Contingent Commission Adjustment) as a result of the determination that an adjustment was necessary to reflect observed favorable paid loss trends. The following table shows the impact to the Consolidated Statements of Comprehensive Income related to these changes in estimates.



	Three Months Ended			Six Months Ended
	June 30, 2015			June 30, 2015
	(in millions, except per share data)
Change in estimate of contingent commission receivable – LPT Agreement	$	2.6		$	2.8
Cumulative adjustment to the Deferred Gain⁽¹⁾	$	(2.4	)	$	(2.6	)
Net income impact of change in estimate	2.4			2.6
EPS impact of change in estimate
Basic and Diluted	0.07			0.08


(1)	The cumulative adjustment to the Deferred Gain was also recognized in losses and LAE incurred in the Consolidated Statement of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised reserves been recognized at the inception of the LPT Agreement.

During the second quarter of 2015, the Company reallocated reserves from non-taxable periods prior to January 1, 2000 to taxable years, which reduced our effective tax rate (Note 6). This change in estimate was the result of the determination that a reallocation of reserves among accident years was appropriate to address the observed loss trends. The following table shows the financial statement impact of this change in estimate.



	Three Months Ended	Six Months Ended
	June 30, 2015	June 30, 2015
	(in millions, except per share data)
Reserves reallocated to taxable years	19.4	19.4
Net income impact of change in estimate	2.5	2.5
EPS impact of change in estimate
Basic and Diluted	0.08	0.08

New Accounting Standards (Notes)	6 Months Ended
New Accounting Standards (Notes)	Jun. 30, 2015
New Accounting Standards [Abstract]
New Accounting Standards	New Accounting Standards In April 2015, the Financial Accounting Standards Board issued Accounting Standards Update (ASU) Number 2015-05, Intangibles - Goodwill and Other - Internal - Use Software (Subtopic 350-40). The update provides guidance to purchasers to assist in determining whether a cloud computing arrangement includes a software license and how to account for such an arrangement. This update becomes effective for annual reporting periods, including interim periods within those annual periods, beginning after December 15, 2015 and early adoption is permitted. The Company does not expect the adoption to have a material impact, if any, on its consolidated financial condition and results of operations. In May 2015, the Financial Accounting Standards Board issued ASU Number 2015-07, Fair Value Measurement (Topic 820). This update removes the requirement to categorize within the fair value hierarchy all investments for which fair value is measured using the net asset value (NAV) per share. Additionally, this update removes the requirement to make certain disclosures for all investments that are eligible to be measured as a practical expedient at fair value using the NAV per share. This update becomes effective for annual reporting periods, including interim periods within those annual periods, beginning after December 15, 2015 and early adoption is permitted. As this update focuses only on disclosures, it will not impact the Company's consolidated financial condition and results of operations. In May 2015, the Financial Accounting Standards Board issued ASU Number 2015-09, Financial Services - Insurance (Topic 944). This update expands the breadth of disclosures that an insurance entity must provide about its short-duration insurance contracts. This expanded disclosure includes the presentation of incurred and paid claims development tables by accident year for a period of up to 10 years. This update becomes effective for annual reporting periods beginning after December 15, 2015 and interim periods beginning after December 15, 2016 and early adoption is permitted. As this update focuses only on disclosures, it will not impact the Company's consolidated financial condition and results of operations.

Fair Value of Financial Instruments

6 Months Ended

Jun. 30, 2015

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:



	June 30, 2015				December 31, 2014
	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value
	(in millions)
Financial assets
Investments	$	2,517.6	$	2,517.6	$	2,448.4	$	2,448.4
Cash and cash equivalents	64.9		64.9		103.6		103.6
Restricted cash and cash equivalents	6.6		6.6		10.8		10.8
Financial liabilities
Notes payable	92.0		95.7		92.0		97.8

Assets and liabilities recorded at fair value on the 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.

Fair values of available-for-sale fixed maturity and equity securities are based on quoted market prices, where available. If quoted market prices and an estimate determined by using objectively verifiable information are unavailable, the Company produces an estimate of fair value based on internally developed valuation techniques, which, depending on the level of observable market inputs, will render the fair value estimate as Level 2 or Level 3. The Company bases all of its estimates of fair value for assets on the bid price, as it represents what a third-party market participant would be willing to pay in an arm's length transaction.

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 financial liabilities are based on a combination of the variable interest rates for the Company's existing line of credit and other 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.

The following table presents the items on the accompanying consolidated balance sheets that are stated at fair value and the corresponding fair value measurements.



	June 30, 2015						December 31, 2014
	Level 1		Level 2		Level 3		Level 1		Level 2		Level 3
	(in millions)
Fixed maturity securities
U.S. Treasuries	$	—	$	158.7	$	—	$	—	$	166.7	$	—
U.S. Agencies	—		38.1		—		—		39.6		—
States and municipalities	—		799.9		—		—		745.8		—
Corporate securities	—		903.7		—		—		908.3		—
Residential mortgage-backed securities	—		262.8		—		—		288.4		—
Commercial mortgage-backed securities	—		60.2		—		—		65.4		—
Asset-backed securities	—		58.4		—		—		61.5		—
Total fixed maturity securities	$	—	$	2,281.8	$	—	$	—	$	2,275.7	$	—
Equity securities	$	217.3	$	—	$	—	$	172.7	$	—	$	—
Short-term investments	$	—	$	18.5	$	—	$	—	$	—	$	—

Investments

6 Months Ended

Jun. 30, 2015

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 June 30, 2015
Fixed maturity securities
U.S. Treasuries	$	153.0	$	5.7	$	—		$	158.7
U.S. Agencies	36.1		2.0		—			38.1
States and municipalities	766.5		36.1		(2.7		)	799.9
Corporate securities	881.2		25.9		(3.4		)	903.7
Residential mortgage-backed securities	255.7		8.5		(1.4		)	262.8
Commercial mortgage-backed securities	60.3		0.5		(0.6		)	60.2
Asset-backed securities	58.4		—		—			58.4
Total fixed maturity securities	2,211.2		78.7		(8.1		)	2,281.8
Equity securities	150.3		71.7		(4.7		)	217.3
Short-term investments	18.5		—		—			18.5
Total investments	$	2,380.0	$	150.4	$	(12.8	)	$	2,517.6



At December 31, 2014
Fixed maturity securities
U.S. Treasuries	$	160.9	$	5.8	$	—		$	166.7
U.S. Agencies	37.2		2.4		—			39.6
States and municipalities	701.6		44.4		(0.2		)	745.8
Corporate securities	880.7		30.8		(3.2		)	908.3
Residential mortgage-backed securities	278.6		10.6		(0.8		)	288.4
Commercial mortgage-backed securities	65.5		0.5		(0.6		)	65.4
Asset-backed securities	61.6		—		(0.1		)	61.5
Total fixed maturity securities	2,186.1		94.5		(4.9		)	2,275.7
Equity securities	97.8		75.5		(0.6		)	172.7
Total investments	$	2,283.9	$	170.0	$	(5.5	)	$	2,448.4

The amortized cost and estimated fair value of fixed maturity securities at June 30, 2015, 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	$	144.9	$	146.0
Due after one year through five years	816.8		850.1
Due after five years through ten years	628.9		649.3
Due after ten years	246.2		255.0
Mortgage and asset-backed securities	374.4		381.4
Total	$	2,211.2	$	2,281.8

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 June 30, 2015 and December 31, 2014.



	June 30, 2015						December 31, 2014
	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
States and municipalities	$	184.4	$	(2.7	)	45	$	20.6	$	(0.2	)	5
Corporate securities	220.8		(2.4		)	82	109.9		(0.8		)	42
Residential mortgage-backed securities	60.9		(1.1		)	23	—		—			—
Commercial mortgage-backed securities	25.8		(0.5		)	9	—		—			—
Total fixed maturity securities	491.9		(6.7		)	159	130.5		(1.0		)	47
Equity securities	70.9		(4.6		)	57	10.1		(0.6		)	15
Total less than 12 months	$	562.8	$	(11.3	)	216	$	140.6	$	(1.6	)	62

12 months or greater:
Fixed maturity securities
Corporate securities	$	41.4	$	(1.0	)	11	$	129.4	$	(2.4	)	39
Residential mortgage-backed securities	9.2		(0.3		)	27	44.1		(0.8		)	36
Commercial mortgage-backed securities	3.0		(0.1		)	2	31.3		(0.6		)	8
Asset-backed securities	—		—			—	18.3		(0.1		)	6
Total fixed maturity securities	53.6		(1.4		)	40	223.1		(3.9		)	89
Equity securities	0.8		(0.1		)	4	—		—			—
Total 12 months or greater	$	54.4	$	(1.5	)	44	$	223.1	$	(3.9	)	89

Total available-for-sale:
Fixed maturity securities
States and municipalities	$	184.4	$	(2.7	)	45	$	20.6	$	(0.2	)	5
Corporate securities	262.2		(3.4		)	93	239.3		(3.2		)	81
Residential mortgage-backed securities	70.1		(1.4		)	50	44.1		(0.8		)	36
Commercial mortgage-backed securities	28.8		(0.6		)	11	31.3		(0.6		)	8
Asset-backed securities	—		—			—	18.3		(0.1		)	6
Total fixed maturity securities	545.5		(8.1		)	199	353.6		(4.9		)	136
Equity securities	71.7		(4.7		)	61	10.1		(0.6		)	15
Total available-for-sale	$	617.2	$	(12.8	)	260	$	363.7	$	(5.5	)	151

Based on reviews of the fixed maturity securities, the Company determined that unrealized losses for the six months ended June 30, 2015 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 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 maturity.

Based on reviews of the equity securities, the Company recognized a total impairment of $0.1 million in the fair value of four equity securities for the six months ended June 30, 2015, as a result of the severity and duration of the change in fair value of the securities. The remaining 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.

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						Six Months Ended
	June 30,						June 30,
	2015			2014			2015			2014
	(in millions)
Net realized gains on investments
Fixed maturity securities
Gross gains	$	0.3		$	0.1		$	0.3		$	0.8
Gross losses	(0.2		)	—			(0.2		)	—
Net realized gains on fixed maturity securities	$	0.1		$	0.1		$	0.1		$	0.8
Equity securities
Gross gains	$	1.9		$	9.1		$	3.5		$	11.6
Gross losses	(0.1		)	—			(0.5		)	—
Net realized gains on equity securities	$	1.8		$	9.1		$	3.0		$	11.6
Total	$	1.9		$	9.2		$	3.1		$	12.4

Change in unrealized gains (losses)
Fixed maturity securities	$	(33.1	)	$	18.0		$	(19.0	)	$	31.3
Equity securities	(6.7		)	(2.6		)	(7.8		)	(3.4		)
Total	$	(39.8	)	$	15.4		$	(26.8	)	$	27.9

Net investment income was as follows:



	Three Months Ended						Six Months Ended
	June 30,						June 30,
	2015			2014			2015			2014
	(in millions)
Fixed maturity securities	$	17.9		$	17.9		$	34.3		$	35.5
Equity securities	1.2			1.0			2.3			2.0
Gross investment income	19.1			18.9			36.6			37.5
Investment expenses	(0.7		)	(0.6		)	(1.3		)	(1.2		)
Net investment income	$	18.4		$	18.3		$	35.3		$	36.3

The Company is required by various state laws and regulations to keep securities or letters of credit in depository accounts with certain states in which it does business. As of June 30, 2015 and December 31, 2014, securities having a fair value of $901.4 million and $783.9 million, respectively, were on deposit. These laws and regulations govern not only the amount, but also the types of securities that are eligible for deposit. The deposits are limited to fixed maturity securities in all states.

Certain reinsurance contracts require Company 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 held in trust for the benefit of ceding reinsurers at June 30, 2015 and December 31, 2014 was $31.0 million and $31.2 million, respectively.

Pursuant to the Third Amended and Restated Credit Agreement with Wells Fargo (Amended Credit Facility), a portion of the Company's debt was secured by fixed maturity securities and restricted cash and cash equivalents that had a fair value of $75.1 million and $74.6 million at June 30, 2015 and December 31, 2014, respectively.

Liability for Unpaid Losses and Loss Adjustment Expenses

6 Months Ended

Jun. 30, 2015

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.



	Six Months Ended
	June 30,
	2015		2014
	(in millions)
Unpaid losses and LAE, gross of reinsurance, at beginning of period	$	2,369.7	$	2,330.5
Less reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE	669.5		743.1
Net unpaid losses and LAE at beginning of period	1,700.2		1,587.4
Losses and LAE, net of reinsurance, incurred during the period related to:
Current period	221.1		252.8
Prior periods	1.4		3.3
Total net losses and LAE incurred during the period	222.5		256.1
Paid losses and LAE, net of reinsurance, related to:
Current period	20.1		19.7
Prior periods	189.0		168.2
Total net paid losses and LAE during the period	209.1		187.9
Ending unpaid losses and LAE, net of reinsurance	1,713.6		1,655.6
Reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE	640.9		699.2
Unpaid losses and LAE, gross of reinsurance, at end of period	$	2,354.5	$	2,354.8

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 $14.8 million and $35.3 million for the six months ended June 30, 2015 and 2014, respectively (Note 8).

The increase in the estimates of incurred losses and LAE attributable to insured events for prior periods was related to the Company's assigned risk business.

LPT Agreement	6 Months Ended
LPT Agreement	Jun. 30, 2015
LPT Agreement [Abstract]
LPT Agreement	LPT Agreement The Company is party to a 100% quota share retroactive reinsurance agreement (LPT Agreement) under which $1.5 billion in liabilities for losses and LAE related to claims incurred by EICN prior to July 1, 1995 were reinsured for consideration of $775.0 million. The LPT Agreement provides coverage up to $2.0 billion. The initial Deferred Gain resulting from the LPT Agreement was recorded as a liability in the accompanying consolidated balance sheets as Deferred reinsurance gain–LPT Agreement. The Company is also entitled to receive a contingent profit commission under the LPT Agreement. The contingent profit commission is an amount based on the favorable difference between actual paid losses and LAE and expected paid losses and LAE as established in the LPT Agreement. 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 on 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 $5.8 million and $6.9 million of the Deferred Gain for the six months ended June 30, 2015 and 2014, respectively. Additionally, the Deferred Gain was reduced by $6.4 million and $20.8 million for the six months ended June 30, 2015 and 2014, respectively, due to a favorable LPT Reserve Adjustment and by $2.6 million and $7.6 million for the six months ended June 30, 2015 and 2014, respectively, due to favorable LPT Contingent Commission Adjustments. The remaining Deferred Gain was $195.1 million and $207.0 million as of June 30, 2015 and December 31, 2014, respectively. The estimated remaining liabilities subject to the LPT Agreement were $511.2 million and $534.8 million as of June 30, 2015 and December 31, 2014, respectively. Losses and LAE paid with respect to the LPT Agreement totaled $682.0 million and $668.4 million from inception through June 30, 2015 and December 31, 2014, respectively.

Stock-Based Compensation

6 Months Ended

Jun. 30, 2015

Stock-Based Compensation [Abstract]

Stock-Based compensation

Stock-Based Compensation

The Company awarded stock options, restricted stock units (RSUs) and performance share units (PSUs) to certain officers 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 2015
Stock options⁽¹⁾	80,800	$	7.63	$	24.20	$	0.6
RSUs⁽¹⁾	89,602	24.20		—		2.2
PSUs⁽²⁾	110,000	24.20		—		2.7

May 2015
RSUs⁽¹⁾	19,904	24.11		—		0.5

(1)

The stock options and RSUs awarded in March 2015 were awarded to certain officers of the Company and vest 25% on March 15, 2016, and each of the subsequent three anniversaries of that date. The stock options and 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 stock options expire seven years from the date of grant.

The RSUs awarded in May 2015 were awarded to non-employee Directors of the Company and have a service vesting period of one year from the date of grant.


(2)	The PSUs awarded in March 2015 were awarded to certain officers 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.

A total of 283,760 and 120,494 stock options were exercised during the six months ended June 30, 2015 and the year ended December 31, 2014, respectively.

Earnings Per Share

6 Months Ended

Jun. 30, 2015

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 assumed issued under the “treasury stock method,” which reflects the potential dilution that would occur if outstanding options were to be exercised. 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				Six Months Ended
	June 30,				June 30,
	2015		2014		2015		2014
	(in millions, except share data)
Net income available to stockholders—basic and diluted	$	29.2	$	45.6	$	43.2	$	56.4
Weighted average number of shares outstanding—basic	32,066,981		31,518,473		31,906,401		31,464,198
Effect of dilutive securities:
PSUs	88,543		263,925		205,697		237,861
Stock options	311,436		213,496		311,168		232,007
RSUs	40,536		35,060		59,964		96,128
Dilutive potential shares	440,515		512,481		576,829		565,996
Weighted average number of shares outstanding—diluted	32,507,496		32,030,954		32,483,230		32,030,194

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 and RSUs that were excluded from diluted earnings per share.



	Three Months Ended		Six Months Ended
	June 30,		June 30,
	2015	2014	2015	2014
Options excluded as the exercise price was greater than the average market price	—	149,100	—	149,100
Options and RSUs excluded under the treasury method as the potential proceeds on settlement or exercise price were greater than the value of shares acquired	345,369	446,974	306,407	154,044

Changes in Estimates (Tables)

6 Months Ended

Jun. 30, 2015

Changes in Estimates [Abstract]

Change to Contingent Profit Commission [Table Text Block]



	Three Months Ended			Six Months Ended
	June 30, 2015			June 30, 2015
	(in millions, except per share data)
Change in estimate of contingent commission receivable – LPT Agreement	$	2.6		$	2.8
Cumulative adjustment to the Deferred Gain⁽¹⁾	$	(2.4	)	$	(2.6	)
Net income impact of change in estimate	2.4			2.6
EPS impact of change in estimate
Basic and Diluted	0.07			0.08


(1)	The cumulative adjustment to the Deferred Gain was also recognized in losses and LAE incurred in the Consolidated Statement of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised reserves been recognized at the inception of the LPT Agreement.

Change Due to Estmated Reserves Ceded Under the LPT Agreement [Table Text Block]



	Three Months Ended			Six Months Ended
	June 30, 2015			June 30, 2015
	(in millions, except per share data)
Change in estimated reserves ceded under the LPT Agreement	$	(10.0	)	$	(10.0	)
Cumulative adjustment to the Deferred Gain⁽¹⁾	(6.4		)	(6.4		)
Net income impact of change in estimate	6.4			6.4
EPS impact of change in estimate
Basic and Diluted	0.20			0.20


(1)	The cumulative adjustment to the Deferred reinsurance gain–LPT Agreement (Deferred Gain) was also recognized in losses and LAE incurred in the Consolidated Statement of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised reserves been recognized at the inception of the LPT Agreement.

Change in Reserves for Non-taxable Periods [Table Text Block]



	Three Months Ended	Six Months Ended
	June 30, 2015	June 30, 2015
	(in millions, except per share data)
Reserves reallocated to taxable years	19.4	19.4
Net income impact of change in estimate	2.5	2.5
EPS impact of change in estimate
Basic and Diluted	0.08	0.08

Fair Value of Financial Instruments (Tables)

6 Months Ended

Jun. 30, 2015

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:



	June 30, 2015				December 31, 2014
	Carrying Value		Estimated Fair Value		Carrying Value		Estimated Fair Value
	(in millions)
Financial assets
Investments	$	2,517.6	$	2,517.6	$	2,448.4	$	2,448.4
Cash and cash equivalents	64.9		64.9		103.6		103.6
Restricted cash and cash equivalents	6.6		6.6		10.8		10.8
Financial liabilities
Notes payable	92.0		95.7		92.0		97.8

Fair value, assets and liabilities measured on recurring basis table

The following table presents the items on the accompanying consolidated balance sheets that are stated at fair value and the corresponding fair value measurements.



	June 30, 2015						December 31, 2014
	Level 1		Level 2		Level 3		Level 1		Level 2		Level 3
	(in millions)
Fixed maturity securities
U.S. Treasuries	$	—	$	158.7	$	—	$	—	$	166.7	$	—
U.S. Agencies	—		38.1		—		—		39.6		—
States and municipalities	—		799.9		—		—		745.8		—
Corporate securities	—		903.7		—		—		908.3		—
Residential mortgage-backed securities	—		262.8		—		—		288.4		—
Commercial mortgage-backed securities	—		60.2		—		—		65.4		—
Asset-backed securities	—		58.4		—		—		61.5		—
Total fixed maturity securities	$	—	$	2,281.8	$	—	$	—	$	2,275.7	$	—
Equity securities	$	217.3	$	—	$	—	$	172.7	$	—	$	—
Short-term investments	$	—	$	18.5	$	—	$	—	$	—	$	—

Investments (Tables)

6 Months Ended

Jun. 30, 2015

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 June 30, 2015
Fixed maturity securities
U.S. Treasuries	$	153.0	$	5.7	$	—		$	158.7
U.S. Agencies	36.1		2.0		—			38.1
States and municipalities	766.5		36.1		(2.7		)	799.9
Corporate securities	881.2		25.9		(3.4		)	903.7
Residential mortgage-backed securities	255.7		8.5		(1.4		)	262.8
Commercial mortgage-backed securities	60.3		0.5		(0.6		)	60.2
Asset-backed securities	58.4		—		—			58.4
Total fixed maturity securities	2,211.2		78.7		(8.1		)	2,281.8
Equity securities	150.3		71.7		(4.7		)	217.3
Short-term investments	18.5		—		—			18.5
Total investments	$	2,380.0	$	150.4	$	(12.8	)	$	2,517.6



At December 31, 2014
Fixed maturity securities
U.S. Treasuries	$	160.9	$	5.8	$	—		$	166.7
U.S. Agencies	37.2		2.4		—			39.6
States and municipalities	701.6		44.4		(0.2		)	745.8
Corporate securities	880.7		30.8		(3.2		)	908.3
Residential mortgage-backed securities	278.6		10.6		(0.8		)	288.4
Commercial mortgage-backed securities	65.5		0.5		(0.6		)	65.4
Asset-backed securities	61.6		—		(0.1		)	61.5
Total fixed maturity securities	2,186.1		94.5		(4.9		)	2,275.7
Equity securities	97.8		75.5		(0.6		)	172.7
Total investments	$	2,283.9	$	170.0	$	(5.5	)	$	2,448.4

Investments classified by contractual maturity date table



	Amortized Cost		Estimated Fair Value
	(in millions)
Due in one year or less	$	144.9	$	146.0
Due after one year through five years	816.8		850.1
Due after five years through ten years	628.9		649.3
Due after ten years	246.2		255.0
Mortgage and asset-backed securities	374.4		381.4
Total	$	2,211.2	$	2,281.8

Unrealized loss on investments table



	June 30, 2015						December 31, 2014
	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
States and municipalities	$	184.4	$	(2.7	)	45	$	20.6	$	(0.2	)	5
Corporate securities	220.8		(2.4		)	82	109.9		(0.8		)	42
Residential mortgage-backed securities	60.9		(1.1		)	23	—		—			—
Commercial mortgage-backed securities	25.8		(0.5		)	9	—		—			—
Total fixed maturity securities	491.9		(6.7		)	159	130.5		(1.0		)	47
Equity securities	70.9		(4.6		)	57	10.1		(0.6		)	15
Total less than 12 months	$	562.8	$	(11.3	)	216	$	140.6	$	(1.6	)	62

12 months or greater:
Fixed maturity securities
Corporate securities	$	41.4	$	(1.0	)	11	$	129.4	$	(2.4	)	39
Residential mortgage-backed securities	9.2		(0.3		)	27	44.1		(0.8		)	36
Commercial mortgage-backed securities	3.0		(0.1		)	2	31.3		(0.6		)	8
Asset-backed securities	—		—			—	18.3		(0.1		)	6
Total fixed maturity securities	53.6		(1.4		)	40	223.1		(3.9		)	89
Equity securities	0.8		(0.1		)	4	—		—			—
Total 12 months or greater	$	54.4	$	(1.5	)	44	$	223.1	$	(3.9	)	89

Total available-for-sale:
Fixed maturity securities
States and municipalities	$	184.4	$	(2.7	)	45	$	20.6	$	(0.2	)	5
Corporate securities	262.2		(3.4		)	93	239.3		(3.2		)	81
Residential mortgage-backed securities	70.1		(1.4		)	50	44.1		(0.8		)	36
Commercial mortgage-backed securities	28.8		(0.6		)	11	31.3		(0.6		)	8
Asset-backed securities	—		—			—	18.3		(0.1		)	6
Total fixed maturity securities	545.5		(8.1		)	199	353.6		(4.9		)	136
Equity securities	71.7		(4.7		)	61	10.1		(0.6		)	15
Total available-for-sale	$	617.2	$	(12.8	)	260	$	363.7	$	(5.5	)	151

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						Six Months Ended
	June 30,						June 30,
	2015			2014			2015			2014
	(in millions)
Net realized gains on investments
Fixed maturity securities
Gross gains	$	0.3		$	0.1		$	0.3		$	0.8
Gross losses	(0.2		)	—			(0.2		)	—
Net realized gains on fixed maturity securities	$	0.1		$	0.1		$	0.1		$	0.8
Equity securities
Gross gains	$	1.9		$	9.1		$	3.5		$	11.6
Gross losses	(0.1		)	—			(0.5		)	—
Net realized gains on equity securities	$	1.8		$	9.1		$	3.0		$	11.6
Total	$	1.9		$	9.2		$	3.1		$	12.4

Change in unrealized gains (losses)
Fixed maturity securities	$	(33.1	)	$	18.0		$	(19.0	)	$	31.3
Equity securities	(6.7		)	(2.6		)	(7.8		)	(3.4		)
Total	$	(39.8	)	$	15.4		$	(26.8	)	$	27.9

Investment income table

Net investment income was as follows:



	Three Months Ended						Six Months Ended
	June 30,						June 30,
	2015			2014			2015			2014
	(in millions)
Fixed maturity securities	$	17.9		$	17.9		$	34.3		$	35.5
Equity securities	1.2			1.0			2.3			2.0
Gross investment income	19.1			18.9			36.6			37.5
Investment expenses	(0.7		)	(0.6		)	(1.3		)	(1.2		)
Net investment income	$	18.4		$	18.3		$	35.3		$	36.3

Liability for Unpaid Losses and Loss Adjustment Expenses (Tables)

6 Months Ended

Jun. 30, 2015

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.



	Six Months Ended
	June 30,
	2015		2014
	(in millions)
Unpaid losses and LAE, gross of reinsurance, at beginning of period	$	2,369.7	$	2,330.5
Less reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE	669.5		743.1
Net unpaid losses and LAE at beginning of period	1,700.2		1,587.4
Losses and LAE, net of reinsurance, incurred during the period related to:
Current period	221.1		252.8
Prior periods	1.4		3.3
Total net losses and LAE incurred during the period	222.5		256.1
Paid losses and LAE, net of reinsurance, related to:
Current period	20.1		19.7
Prior periods	189.0		168.2
Total net paid losses and LAE during the period	209.1		187.9
Ending unpaid losses and LAE, net of reinsurance	1,713.6		1,655.6
Reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE	640.9		699.2
Unpaid losses and LAE, gross of reinsurance, at end of period	$	2,354.5	$	2,354.8

Stock-Based Compensation Stock-Based Compensation (Tables)

6 Months Ended

Jun. 30, 2015

Stock-Based Compensation [Abstract]

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

The Company awarded stock options, restricted stock units (RSUs) and performance share units (PSUs) to certain officers 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 2015
Stock options⁽¹⁾	80,800	$	7.63	$	24.20	$	0.6
RSUs⁽¹⁾	89,602	24.20		—		2.2
PSUs⁽²⁾	110,000	24.20		—		2.7

May 2015
RSUs⁽¹⁾	19,904	24.11		—		0.5

(1)

The RSUs awarded in May 2015 were awarded to non-employee Directors of the Company and have a service vesting period of one year from the date of grant.


(2)	The PSUs awarded in March 2015 were awarded to certain officers 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)

6 Months Ended

Jun. 30, 2015

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				Six Months Ended
	June 30,				June 30,
	2015		2014		2015		2014
	(in millions, except share data)
Net income available to stockholders—basic and diluted	$	29.2	$	45.6	$	43.2	$	56.4
Weighted average number of shares outstanding—basic	32,066,981		31,518,473		31,906,401		31,464,198
Effect of dilutive securities:
PSUs	88,543		263,925		205,697		237,861
Stock options	311,436		213,496		311,168		232,007
RSUs	40,536		35,060		59,964		96,128
Dilutive potential shares	440,515		512,481		576,829		565,996
Weighted average number of shares outstanding—diluted	32,507,496		32,030,954		32,483,230		32,030,194

Antidilutive securities excluded from computation of earnings per share table

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



	Three Months Ended		Six Months Ended
	June 30,		June 30,
	2015	2014	2015	2014
Options excluded as the exercise price was greater than the average market price	—	149,100	—	149,100
Options and RSUs excluded under the treasury method as the potential proceeds on settlement or exercise price were greater than the value of shares acquired	345,369	446,974	306,407	154,044

Changes in Estimates (Details) (USD $)

3 Months Ended

6 Months Ended

Jun. 30, 2015

Jun. 30, 2014

Jun. 30, 2015

Jun. 30, 2014

Change in Accounting Estimate [Line Items]

Net income

$ 29,200,000

$ 45,600,000

$ 43,200,000

$ 56,400,000

Change Due to Estimated Reserves Ceded Under the LPT Agreement [Member]

Change in Accounting Estimate [Line Items]

Change to estimated reserves ceded under the LPT agreement

(10,000,000)

Cumulative adjustment to the Deferred Gain

(6,400,000)

^[1]

(6,400,000)

^[1]

(20,800,000)

Net income

6,400,000

Basic and Diluted

$ 0.20

Change to Contingent Profit Commission [Member]

Change in Accounting Estimate [Line Items]

Change in estimate of contingent commission receivable - LPT Agreement

2,600,000

2,800,000

Cumulative adjustment to the Deferred Gain

(2,400,000)

^[2]

(2,600,000)

^[2]

(7,600,000)

Net income

2,400,000

2,600,000

Basic and Diluted

$ 0.07

$ 0.08

Due to change in reserves for non-taxable Periods [Member]

Change in Accounting Estimate [Line Items]

Reserves reallocated to taxable years

19,400,000

Net income

$ 2,500,000

Basic and Diluted

$ 0.08

[1]	The cumulative adjustment to the Deferred reinsurance gain–LPT Agreement (Deferred Gain) was also recognized in losses and LAE incurred in the Consolidated Statement of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised reserves been recognized at the inception of the LPT Agreement.
[2]	The cumulative adjustment to the Deferred Gain was also recognized in losses and LAE incurred in the Consolidated Statement of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised reserves been recognized at the inception of the LPT Agreement.

Fair Value of Financial Instruments (Details) (USD $)	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	$ 2,517,600,000	$ 2,448,400,000
Investments, fair value	2,517,600,000	2,448,400,000
Cash and cash equivalents	64,900,000	103,600,000	37,000,000	34,500,000
Cash and cash equivalents, estimated fair value	64,900,000	103,600,000
Restricted cash and cash equivalents	6,600,000	10,800,000
Notes payable	92,000,000	92,000,000
Notes Payable, fair value	95,700,000	97,800,000
Estimate of Fair Value, Fair Value Disclosure [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Investments	31,000,000	31,200,000
Restricted cash and cash equivalents	$ 6,600,000	$ 10,800,000

Fair Value of Financial Instruments, Fair Value Inputs (Details) (USD $) In Millions, unless otherwise specified	Jun. 30, 2015	Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	$ 2,517.6	$ 2,448.4
Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	2,281.8	2,275.7
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
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	2,281.8	2,275.7
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
US Treasury Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	158.7	166.7
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
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		166.7
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
US Government Agencies Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	38.1	39.6
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
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		39.6
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
US States and Political Subdivisions Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	799.9	745.8
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
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		745.8
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
Corporate Debt Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	903.7	908.3
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
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		908.3
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
Residential Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	262.8	288.4
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
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		288.4
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
Commercial Mortgage Backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	60.2	65.4
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
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		65.4
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
Asset-backed Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	58.4	61.5
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
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		61.5
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
Equity Securities [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investments	217.3	172.7
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		172.7
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
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	0	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
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	18.5	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

Investments (Details) (USD $)	Jun. 30, 2015	Dec. 31, 2014
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	$ 2,380,000,000	$ 2,283,900,000
Gross unrealized gain	150,400,000	170,000,000
Gross unrealized loss	(12,800,000)	(5,500,000)
Investments	2,517,600,000	2,448,400,000
Deposit Assets
Investments	2,517,600,000	2,448,400,000
Assets Held-in-trust
Investments	2,517,600,000	2,448,400,000
Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	2,211,200,000	2,186,100,000
Gross unrealized gain	78,700,000	94,500,000
Gross unrealized loss	(8,100,000)	(4,900,000)
Investments	2,281,800,000	2,275,700,000
Deposit Assets
Investments	2,281,800,000	2,275,700,000
Assets Held-in-trust
Investments	2,281,800,000	2,275,700,000
US Treasury Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	153,000,000	160,900,000
Gross unrealized gain	5,700,000	5,800,000
Gross unrealized loss	0	0
Investments	158,700,000	166,700,000
Deposit Assets
Investments	158,700,000	166,700,000
Assets Held-in-trust
Investments	158,700,000	166,700,000
US Government Agencies Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	36,100,000	37,200,000
Gross unrealized gain	2,000,000	2,400,000
Gross unrealized loss	0	0
Investments	38,100,000	39,600,000
Deposit Assets
Investments	38,100,000	39,600,000
Assets Held-in-trust
Investments	38,100,000	39,600,000
US States and Political Subdivisions Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	766,500,000	701,600,000
Gross unrealized gain	36,100,000	44,400,000
Gross unrealized loss	(2,700,000)	(200,000)
Investments	799,900,000	745,800,000
Deposit Assets
Investments	799,900,000	745,800,000
Assets Held-in-trust
Investments	799,900,000	745,800,000
Corporate Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	881,200,000	880,700,000
Gross unrealized gain	25,900,000	30,800,000
Gross unrealized loss	(3,400,000)	(3,200,000)
Investments	903,700,000	908,300,000
Deposit Assets
Investments	903,700,000	908,300,000
Assets Held-in-trust
Investments	903,700,000	908,300,000
Residential Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	255,700,000	278,600,000
Gross unrealized gain	8,500,000	10,600,000
Gross unrealized loss	(1,400,000)	(800,000)
Investments	262,800,000	288,400,000
Deposit Assets
Investments	262,800,000	288,400,000
Assets Held-in-trust
Investments	262,800,000	288,400,000
Commercial Mortgage Backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	60,300,000	65,500,000
Gross unrealized gain	500,000	500,000
Gross unrealized loss	(600,000)	(600,000)
Investments	60,200,000	65,400,000
Deposit Assets
Investments	60,200,000	65,400,000
Assets Held-in-trust
Investments	60,200,000	65,400,000
Asset-backed Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	58,400,000	61,600,000
Gross unrealized gain	0	0
Gross unrealized loss	0	(100,000)
Investments	58,400,000	61,500,000
Deposit Assets
Investments	58,400,000	61,500,000
Assets Held-in-trust
Investments	58,400,000	61,500,000
Equity Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	150,300,000	97,800,000
Gross unrealized gain	71,700,000	75,500,000
Gross unrealized loss	(4,700,000)	(600,000)
Investments	217,300,000	172,700,000
Deposit Assets
Investments	217,300,000	172,700,000
Assets Held-in-trust
Investments	217,300,000	172,700,000
Short-term Investments [Member]
Schedule of Available-for-sale Securities [Line Items]
Amortized cost	18,500,000
Gross unrealized gain	0
Gross unrealized loss	0
Fair Value Measurement [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments	31,000,000	31,200,000
Deposit Assets
Investments	31,000,000	31,200,000
Assets Held-in-trust
Investments	31,000,000	31,200,000
Fair Value Measurement [Member] \| Debt Securities [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments	901,400,000	783,900,000
Deposit Assets
Investments	901,400,000	783,900,000
Assets Held-in-trust
Investments	901,400,000	783,900,000
Fair Value Measurement [Member] \| Fixed Maturities and Restricted Cash Equivalents [Member]
Schedule of Available-for-sale Securities [Line Items]
Investments	75,100,000	74,600,000
Deposit Assets
Investments	75,100,000	74,600,000
Assets Held-in-trust
Investments	$ 75,100,000	$ 74,600,000

Investments, Amortized Cost and Estimated Fair Value (Details) (USD $)	Jun. 30, 2015	Dec. 31, 2014
Amortized Cost
Due in one year or less, amortized cost	$ 144,900,000
Due after one year through five years, amortized cost	816,800,000
Due after five years through ten years, amortized cost	628,900,000
Due after ten years, amortized cost	246,200,000
Mortgage and asset-backed securities, amortized cost	374,400,000
Total, amortized cost	2,211,200,000
Estimated Fair Value
Due in one year or less, fair value	146,000,000
Due after one year through five years, fair value	850,100,000
Due after five years through ten years, fair value	649,300,000
Due after ten years, fair value	255,000,000
Mortgage and asset-backed securities, fair value	381,400,000
Total, fair value	$ 2,281,800,000	$ 2,275,700,000

Investments, Continuous Loss Position (Details) (USD $)	6 Months Ended
Investments, Continuous Loss Position (Details) (USD $)	Jun. 30, 2015	Dec. 31, 2014
Estimated Fair Value
Estimated fair value, less than 12 months	$ 562,800,000	$ 140,600,000
Estimated fair value, 12 months or greater	54,400,000	223,100,000
Estimated fair value, total	617,200,000	363,700,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(11,300,000)	(1,600,000)
Gross unrealized losses, 12 months or greater	1,500,000	3,900,000
Estimated unrealized losses, total	(12,800,000)	(5,500,000)
Number of issues in loss position, less than 12 months	216	62
Number of Issues in loss position, 12 months or greater	44	89
Number of issues loss position, aggregate	260	151
Total impairments, value	100,000
Total impairments, number of securities	4
Debt Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	491,900,000	130,500,000
Estimated fair value, 12 months or greater	53,600,000	223,100,000
Estimated fair value, total	545,500,000	353,600,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(6,700,000)	(1,000,000)
Gross unrealized losses, 12 months or greater	1,400,000	3,900,000
Estimated unrealized losses, total	(8,100,000)	(4,900,000)
Number of issues in loss position, less than 12 months	159	47
Number of Issues in loss position, 12 months or greater	40	89
Number of issues loss position, aggregate	199	136
US States and Political Subdivisions Debt Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	184,400,000	20,600,000
Estimated fair value, total	184,400,000	20,600,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(2,700,000)	(200,000)
Estimated unrealized losses, total	(2,700,000)	(200,000)
Number of issues in loss position, less than 12 months	45	5
Number of issues loss position, aggregate	45	5
Corporate Debt Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	220,800,000	109,900,000
Estimated fair value, 12 months or greater	41,400,000	129,400,000
Estimated fair value, total	262,200,000	239,300,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(2,400,000)	(800,000)
Gross unrealized losses, 12 months or greater	1,000,000	2,400,000
Estimated unrealized losses, total	(3,400,000)	(3,200,000)
Number of issues in loss position, less than 12 months	82	42
Number of Issues in loss position, 12 months or greater	11	39
Number of issues loss position, aggregate	93	81
Residential Mortgage Backed Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	60,900,000	0
Estimated fair value, 12 months or greater	9,200,000	44,100,000
Estimated fair value, total	70,100,000	44,100,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(1,100,000)	0
Gross unrealized losses, 12 months or greater	300,000	800,000
Estimated unrealized losses, total	(1,400,000)	(800,000)
Number of issues in loss position, less than 12 months	23	0
Number of Issues in loss position, 12 months or greater	27	36
Number of issues loss position, aggregate	50	36
Commercial Mortgage Backed Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	25,800,000	0
Estimated fair value, 12 months or greater	3,000,000	31,300,000
Estimated fair value, total	28,800,000	31,300,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(500,000)	0
Gross unrealized losses, 12 months or greater	100,000	600,000
Estimated unrealized losses, total	(600,000)	(600,000)
Number of issues in loss position, less than 12 months	9	0
Number of Issues in loss position, 12 months or greater	2	8
Number of issues loss position, aggregate	11	8
Asset-backed Securities [Member]
Estimated Fair Value
Estimated fair value, 12 months or greater	0	18,300,000
Estimated fair value, total	0	18,300,000
Gross Unrealized Losses
Gross unrealized losses, 12 months or greater	0	100,000
Estimated unrealized losses, total	0	(100,000)
Number of Issues in loss position, 12 months or greater	0	6
Number of issues loss position, aggregate	0	0
Equity Securities [Member]
Estimated Fair Value
Estimated fair value, less than 12 months	70,900,000	10,100,000
Estimated fair value, 12 months or greater	800,000	0
Estimated fair value, total	71,700,000	10,100,000
Gross Unrealized Losses
Gross unrealized losses, less than 12 months	(4,600,000)	(600,000)
Gross unrealized losses, 12 months or greater	100,000	0
Estimated unrealized losses, total	(4,700,000)	(600,000)
Number of issues in loss position, less than 12 months	57	15
Number of Issues in loss position, 12 months or greater	4	0
Number of issues loss position, aggregate	$ 61	$ 15

Investments, Net Realized Gains (Losses) (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Net realized gains (losses)
Net realized gains (losses) on fixed maturity and equity securities	$ 1.9	$ 9.2	$ 3.1	$ 12.4
Change in unrealized gains (losses)
Change in unrealized gains (losses) on fixed maturity and equity securities	(39.8)	15.4	(26.8)	27.9
Debt Securities [Member]
Net realized gains (losses)
Gross gains from sales	0.3	0.1	0.3	0.8
Gross losses from sales	0.2	0	0.2	0
Net realized gains (losses) on fixed maturity and equity securities	0.1	0.1	0.1	0.8
Change in unrealized gains (losses)
Change in unrealized gains (losses) on fixed maturity and equity securities	(33.1)	18.0	(19.0)	31.3
Equity Securities [Member]
Net realized gains (losses)
Gross gains from sales	1.9	9.1	3.5	11.6
Gross losses from sales	0.1	0	0.5	0
Net realized gains (losses) on fixed maturity and equity securities	1.8	9.1	3.0	11.6
Change in unrealized gains (losses)
Change in unrealized gains (losses) on fixed maturity and equity securities	$ (6.7)	$ (2.6)	$ (7.8)	$ (3.4)

Net Investment Income (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income	$ 19.1	$ 18.9	$ 36.6	$ 37.5
Investment expenses	0.7	0.6	1.3	1.2
Net investment income	18.4	18.3	35.3	36.3
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	17.9	17.9	34.3	35.5
Equity Securities [Member]
Schedule of Investment Income, Reported Amounts, by Category [Line Items]
Investment income related to equity securities	$ 1.2	$ 1.0	$ 2.3	$ 2.0

Income Taxes (Details)	6 Months Ended
Income Taxes (Details)	Jun. 30, 2015	Jun. 30, 2014
Effective Income Tax Rate, Continuing Operations, Tax Rate Reconciliation [Abstract]
Expense computed at statutory rate	35.00%	35.00%
Dividends received deduction and tax-exempt interest	(8.00%)	(9.80%)
LPT deferred gain amortization	(4.50%)	(8.00%)
LPT reserve adjustment	(2.10%)	(8.10%)
Pre-privatization reserve adjustment, excluding LPT	(4.90%)	(3.70%)
Other	0.50%	0.10%
Effective tax rate	16.00%	5.50%

Liability for Unpaid Losses and Loss Adjustment Expenses (Details) (USD $)	3 Months Ended	6 Months Ended
	Jun. 30, 2015	Jun. 30, 2015	Dec. 31, 2014	Jun. 30, 2014	Dec. 31, 2013
Liability for Unpaid Claims and Claims Adjustment Expense [Roll Forward]
Unpaid losses and LAE, gross of reinsurance, at beginning of period		$ 2,369,700,000		$ 2,354,800,000	$ 2,330,500,000
Less reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE		669,500,000		699,200,000	743,100,000
Net unpaid losses and LAE at beginning of period		1,700,200,000		1,655,600,000	1,587,400,000
Losses and LAE, net of reinsurance, incurred during the period related to:
Current period	252,800,000	221,100,000
Prior periods	3,300,000	1,400,000
Total net losses and LAE incurred during the period	256,100,000	222,500,000
Deduct payments for losses and LAE, net of reinsurance, related to:
Current period	19,700,000	20,100,000
Prior periods	168,200,000	189,000,000
Total net paid losses and LAE during the period	187,900,000	209,100,000
Ending unpaid losses and LAE, net of reinsurance	1,713,600,000	1,713,600,000		1,655,600,000	1,587,400,000
Reinsurance recoverable, excluding bad debt allowance, on unpaid losses and LAE	640,900,000	640,900,000		699,200,000	743,100,000
Unpaid losses and LAE, gross of reinsurance, at end of period	2,354,500,000	2,354,500,000		2,354,800,000	2,330,500,000
LPT Agreement [Abstract]
Impact of the LPT Agreement	$ 14,800,000	$ 14,800,000	$ 35,300,000

LPT Agreement LPT Agreement (Details) (USD $)

6 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

6 Months Ended

Jun. 30, 2015

Jun. 30, 2014

Dec. 31, 2014

Jun. 30, 2015

Change Due to Estimated Reserves Ceded Under the LPT Agreement [Member]

Jun. 30, 2015

Change Due to Estimated Reserves Ceded Under the LPT Agreement [Member]

Jun. 30, 2014

Change Due to Estimated Reserves Ceded Under the LPT Agreement [Member]

Jun. 30, 2015

Change to Contingent Profit Commission [Member]

Jun. 30, 2015

Change to Contingent Profit Commission [Member]

Jun. 30, 2014

Change to Contingent Profit Commission [Member]

Jun. 30, 2015

Indemnification Agreement [Member]

Reinsurance Agreement [Line Items]

Reinsurance quota share, percentage

100.00%

Liabilities for the incurred but unpaid losses and LAE related to claims prior to July 1, 1995

$ 1,500,000,000

Ceded premiums written

775,000,000

Coverage provided under LPT Agreement

2,000,000,000

Amortization of deferred gain

5,800,000

6,900,000

Cumulative adjustment to the Deferred Gain

6,400,000

^[1]

6,400,000

^[1]

20,800,000

2,400,000

^[2]

2,600,000

^[2]

7,600,000

Deferred reinsurance gain—LPT Agreement

195,100,000

207,000,000

Estimated remaining liabilities - LPT Agreement

511,200,000

534,800,000

Paid losses and LAE claims related to LPT

$ 682,000,000

$ 668,400,000

[1]	The cumulative adjustment to the Deferred reinsurance gain–LPT Agreement (Deferred Gain) was also recognized in losses and LAE incurred in the Consolidated Statement of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised reserves been recognized at the inception of the LPT Agreement.
[2]	The cumulative adjustment to the Deferred Gain was also recognized in losses and LAE incurred in the Consolidated Statement of Comprehensive Income, so that the Deferred Gain reflects the balance that would have existed had the revised reserves been recognized at the inception of the LPT Agreement.

Accumulated Other Comprehensive Income (Details) (USD $)	Jun. 30, 2015	Dec. 31, 2014
Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract]
Net unrealized gain on investments, before taxes	$ 137,700,000	$ 164,500,000
Deferred tax expense on net unrealized gains	(48,200,000)	(57,600,000)
Total accumulated other comprehensive income, net	$ 89,500,000	$ 106,900,000

Stock-Based Compensation (Details) (USD $)
In Millions, except Share data, unless otherwise specified

6 Months Ended

12 Months Ended

3 Months Ended

6 Months Ended

3 Months Ended

1 Months Ended

3 Months Ended

1 Months Ended

3 Months Ended

Jun. 30, 2015

Dec. 31, 2014

Mar. 31, 2015

Officer [Member]

Jun. 30, 2015

Officer [Member]

Mar. 31, 2015

Stock Option [Member]

Mar. 31, 2015

Stock Option [Member]

Officer [Member]

May 31, 2015

Restricted Stock Units (RSUs) [Member]

Mar. 31, 2015

Restricted Stock Units (RSUs) [Member]

May 31, 2015

Restricted Stock Units (RSUs) [Member]

Director [Member]

Mar. 31, 2015

Performance Shares [Member]

Mar. 31, 2015

Performance Shares [Member]

Officer [Member]

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

Share-based compensation award, shares issued

80,800

^[1]

19,904

^[1]

89,602

^[1]

110,000

^[2]

Share-based compensation options, exercise price on grant date

$ 7.63

^[1]

$ 24.11

^[1]

$ 24.20

^[2]

$ 24.20

^[2]

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

$ 24.20

^[1]

$ 0

Fair value of awards awarded on grant date

$ 0.6

^[1]

$ 0.5

^[1]

$ 2.2

^[1]

$ 2.7

^[2]

Vesting rights for options awarded

vest 25% on March 15, 2016, and each of the subsequent three anniversaries of that date

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

7 years 0 months 0 days

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

1 year 0 months 0 days

Performance share awards performance period

two years

Performance share awards, minimum payout

0.00%

Performance share awards, maximum payout

200.00%

Stock-options exercised

283,760

120,494

[1]

[2]

The PSUs awarded in March 2015 were awarded to certain officers 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, except Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Earnings Per Share, Basic and Diluted, by Common Class [Line Items]
Net income available to stockholders - basic and diluted	$ 29,200	$ 45,600	$ 43,200	$ 56,400
Weighted average number of shares outstanding - basic	32,066,981	31,518,473	31,906,401	31,464,198
Effect of dilutive securities:
Dilutive securities	440,515	512,481	576,829	565,996
Weighted average number of shares outstanding - diluted	32,507,496	32,030,954	32,483,230	32,030,194
Antidilutive securities excluded from computation of earnings per share	0	149,100	0	149,100
Antidilutive securites excluded under the treasury method from computation of earnings per share	345,369	446,974	306,407	154,044
Employee Stock Option [Member]
Effect of dilutive securities:
Dilutive securities	311,436	213,496	311,168	232,007
Restricted Stock Units (RSUs) [Member]
Effect of dilutive securities:
Dilutive securities	40,536	35,060	59,964	96,128
Performance Shares [Member]
Effect of dilutive securities:
Dilutive securities	88,543	263,925	205,697	237,861

Conolidated Statements of Comprehensive Income (Parentheticals) (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Income Statement Parenthetical [Abstract]
Other comprehensive income (loss), unrealized holding gain (loss) on securities arising during period, tax	$ (13,300)	$ 8,600	$ (8,300)	$ 14,100
Other comprehensive income (loss), reclassification adjustment for sale of securities included in net income, tax	$ 700	$ 3,200	$ 1,100	$ 4,300

Basis of Presentation (Details)	6 Months Ended
Basis of Presentation (Details)	Jun. 30, 2015
Basis of Presentation [Abstract]
Number of Operating Segments	1