v3.10.0.1
Document and Entity Information - USD ($)
12 Months Ended
Dec. 31, 2018
Feb. 14, 2019
Jun. 30, 2018
Document and Entity Information [Abstract]      
Document Type 10-K    
Amendment Flag false    
Document Period End Date Dec. 31, 2018    
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 Emerging Growth Company false    
Entity Small Business false    
Entity Current Reporting Status Yes    
Entity Filer Category Large Accelerated Filer    
Entity Shell Company false    
Entity Common Stock Shares Outstanding   32,829,863  
Entity Public Float     $ 1,109,698,729
Document Fiscal Year Focus 2018    
Document Fiscal Period Focus FY