v3.3.1.900
Segment Information - Net Income (Loss) and Total Assets (Details)
$ in Thousands
 3 Months Ended 12 Months Ended
Dec. 31, 2015
USD ($)
Sep. 30, 2015
USD ($)
Jun. 30, 2015
USD ($)
Mar. 31, 2015
USD ($)
Dec. 31, 2014
USD ($)
Sep. 30, 2014
USD ($)
Jun. 30, 2014
USD ($)
Mar. 31, 2014
USD ($)
Dec. 31, 2015
USD ($)
Segment
Dec. 31, 2014
USD ($)
Dec. 31, 2013
USD ($)
Dec. 31, 2012
USD ($)
Segment Reporting Information [Line Items]                        
Number of reportable segments | Segment                 2      
Income Statement [Abstract]                        
Gross premiums written                 $ 2,662,825 $ 2,507,352 $ 2,204,159  
Net premiums written                 2,514,116 2,458,136 2,096,301  
Net premiums earned                 2,429,069 2,251,743 2,000,887  
Other insurance revenue                 11,512 13,410 14,232  
Net loss and loss adjustment expenses                 (1,633,570) (1,498,271) (1,349,630)  
Commission and other acquisition expenses                 (724,197) (659,315) (556,578)  
General and administrative expenses                 (40,497) (42,148) (39,922)  
Underwriting (loss) income                 42,317 65,419 68,989  
Reconciliation to net income                        
Net investment income and realized gains on investment                 133,590 118,378 94,937  
Net impairment losses recognized in earnings                 (1,060) (2,364) 0  
Interest and amortization expenses                 (29,063) (29,959) (39,805)  
Accelerated amortization of junior subordinated debt discount and issuance cost                 0 (28,240) 0  
Amortization of intangible assets                 (2,840) (3,277) (3,780)  
Foreign exchange and other gains                 7,753 4,150 2,809  
Other general and administrative expenses                 (24,375) (20,410) (18,431)  
Income tax expense                 (2,038) (2,164) (1,863)  
Net income $ 30,724 $ 28,515 $ 26,511 $ 38,534 $ 33,631 $ 33,926 $ 31,915 $ 2,061 $ 124,284 $ 101,533 $ 102,856  
Net loss and LAE ratio                 66.90% 66.10% 67.00%  
Commission and other acquisition expense ratio                 29.70% 29.10% 27.60%  
General and administrative expense ratio                 2.70% 2.80% 2.90%  
Combined ratio                 99.30% 98.00% 97.50%  
Assets [Abstract]                        
Reinsurance balance receivable, net 377,318       512,996       $ 377,318 $ 512,996    
Reinsurance recoverable on unpaid losses 71,248       75,873       71,248 75,873 $ 84,036 $ 110,858
Deferred commissions and other acquisition expenses 397,548       372,487       397,548 372,487    
Loan to related party 167,975       167,975       167,975 167,975    
Goodwill and intangible assets, net 81,920       87,336       81,920 87,336 90,613  
Restricted cash and cash equivalents and investments 3,668,444       3,121,343       3,668,444 3,121,343    
Other assets 125,105       57,926       125,105 57,926    
Total assets 5,713,645       5,164,092       5,713,645 5,164,092    
Diversified Reinsurance segment                        
Income Statement [Abstract]                        
Gross premiums written                 776,852 897,748 848,790  
Net premiums written                 734,781 850,049 763,374  
Net premiums earned                 744,875 854,026 753,157  
Other insurance revenue                 11,512 13,410 14,232  
Net loss and loss adjustment expenses                 (547,296) (579,771) (519,962)  
Commission and other acquisition expenses                 (196,292) (233,711) (190,604)  
General and administrative expenses                 (37,550) (38,858) (37,649)  
Underwriting (loss) income                 $ (24,751) $ 15,096 $ 19,174  
Reconciliation to net income                        
Net loss and LAE ratio                 72.30% 66.80% 67.80%  
Commission and other acquisition expense ratio                 26.00% 26.90% 24.80%  
General and administrative expense ratio                 5.00% 4.60% 4.90%  
Combined ratio                 103.30% 98.30% 97.50%  
Assets [Abstract]                        
Reinsurance balance receivable, net 230,223       245,782       $ 230,223 $ 245,782    
Reinsurance recoverable on unpaid losses 38,390       31,272       38,390 31,272    
Deferred commissions and other acquisition expenses 80,012       87,289       80,012 87,289    
Loan to related party 0       0       0 0    
Goodwill and intangible assets, net 81,920       87,336       81,920 87,336    
Restricted cash and cash equivalents and investments 1,178,076       1,132,953       1,178,076 1,132,953    
Other assets 35,920       40,032       35,920 40,032    
Total assets - reportable segments 1,644,541       1,624,664       1,644,541 1,624,664    
Corporate assets 0       0       0 0    
Total assets 1,644,541       1,624,664       1,644,541 1,624,664    
AmTrust Reinsurance segment                        
Income Statement [Abstract]                        
Gross premiums written                 1,885,974 1,610,485 $ 1,169,961  
Net premiums written                 1,779,334 1,610,485 1,169,961  
Net premiums earned                 1,684,191 1,378,327 988,900  
Other insurance revenue                 0 0 0  
Net loss and loss adjustment expenses                 (1,074,072) (893,502) (653,528)  
Commission and other acquisition expenses                 (527,863) (418,908) (291,559)  
General and administrative expenses                 (2,947) (2,533) (1,566)  
Underwriting (loss) income                 $ 79,309 $ 63,384 $ 42,247  
Reconciliation to net income                        
Net loss and LAE ratio                 63.80% 64.80% 66.10%  
Commission and other acquisition expense ratio                 31.30% 30.40% 29.50%  
General and administrative expense ratio                 0.20% 0.20% 0.20%  
Combined ratio                 95.30% 95.40% 95.80%  
Assets [Abstract]                        
Reinsurance balance receivable, net 137,586       256,779       $ 137,586 $ 256,779    
Reinsurance recoverable on unpaid losses 14,230       0       14,230 0    
Deferred commissions and other acquisition expenses 317,536       285,232       317,536 285,232    
Loan to related party 167,975       167,975       167,975 167,975    
Goodwill and intangible assets, net 0       0       0 0    
Restricted cash and cash equivalents and investments 2,468,689       1,930,502       2,468,689 1,930,502    
Other assets 72,843       0       72,843 0    
Total assets - reportable segments 3,178,859       2,640,488       3,178,859 2,640,488    
Corporate assets 0       0       0 0    
Total assets 3,178,859       2,640,488       3,178,859 2,640,488    
Other                        
Income Statement [Abstract]                        
Gross premiums written                 (1) (881) $ 185,408  
Net premiums written                 1 (2,398) 162,966  
Net premiums earned                 3 19,390 258,830  
Other insurance revenue                 0 0 0  
Net loss and loss adjustment expenses                 (12,202) (24,998) (176,140)  
Commission and other acquisition expenses                 (42) (6,696) (74,415)  
General and administrative expenses                 0 (757) (707)  
Underwriting (loss) income                 $ (12,241) $ (13,061) $ 7,568  
Reconciliation to net income                        
Combined ratio                  
Total reportable segments                        
Assets [Abstract]                        
Reinsurance balance receivable, net 367,809       502,561       $ 367,809 $ 502,561    
Reinsurance recoverable on unpaid losses 52,620       31,272       52,620 31,272    
Deferred commissions and other acquisition expenses 397,548       372,521       397,548 372,521    
Loan to related party 167,975       167,975       167,975 167,975    
Goodwill and intangible assets, net 81,920       87,336       81,920 87,336    
Restricted cash and cash equivalents and investments 3,646,765       3,063,455       3,646,765 3,063,455    
Other assets 108,763       40,032       108,763 40,032    
Total assets - reportable segments 4,823,400       4,265,152       4,823,400 4,265,152    
Corporate assets 890,245       898,940       890,245 898,940    
Total assets $ 5,713,645       $ 5,164,092       $ 5,713,645 $ 5,164,092