v2.4.0.8
Segments - Net Income (Loss) and Total Assets (Details) (USD $)
In Thousands, unless otherwise specified
 3 Months Ended
Mar. 31, 2014
Segment
Mar. 31, 2013
Dec. 31, 2013
Segment Reporting Information [Line Items]      
Number of operating segments 3    
Net Income (Loss) [Abstract]      
Net premiums written $ 709,892 $ 689,059  
Net premiums earned 519,230 488,442  
Other insurance revenue 5,162 5,215  
Net loss and loss adjustment expenses (351,344) (334,895)  
Commission and other acquisition expenses (146,082) (132,330)  
General and administrative expenses (11,737) (11,461)  
Underwriting income (loss) 15,229 14,971  
Reconciliation to net income      
Net investment income and realized gains on investment 27,930 25,262  
Amortization of intangible assets (819) (945)  
Foreign exchange and other gains 138 1,547  
Interest and amortization expenses (8,064) (9,570)  
Accelerated amortization of junior subordinated debt discount and issuance cost (28,240) 0  
Other general and administrative expenses (3,187) (2,634)  
Income tax expense (926) (524)  
Net income 2,061 28,107  
Net loss and loss adjustment expense ratio 67.00% [1] 67.80% [1]  
Commission and other acquisition expense ratio 27.90% [2] 26.80% [2]  
General and administrative expense ratio 2.80% [3] 2.90% [3]  
Combined ratio 97.70% [4] 97.50% [4]  
Assets [Abstract]      
Reinsurance balance receivable, net 675,219   560,145
Prepaid reinsurance premiums 31,870   39,186
Reinsurance recoverable on unpaid losses 83,350   84,036
Deferred commissions and other acquisition expenses 348,716   304,908
Loan to related party 167,975   167,975
Goodwill and intangible assets, net 89,794   90,613
Restricted cash and cash equivalents and investments 2,360,511   2,231,698
Other assets 28,617   32,358
Total Assets - operating segments 3,786,052   3,510,919
Corporate assets 1,082,504   1,202,460
Total assets 4,868,556   4,713,379
Diversified Reinsurance Segment [Member]
      
Net Income (Loss) [Abstract]      
Net premiums written 291,619 267,610  
Net premiums earned 199,316 196,249  
Other insurance revenue 5,162 5,215  
Net loss and loss adjustment expenses (141,364) (140,763)  
Commission and other acquisition expenses (50,841) (44,782)  
General and administrative expenses (10,990) (10,798)  
Underwriting income (loss) 1,283 5,121  
Reconciliation to net income      
Net loss and loss adjustment expense ratio 69.10% [1] 69.90% [1]  
Commission and other acquisition expense ratio 24.90% [2] 22.20% [2]  
General and administrative expense ratio 5.40% [3] 5.40% [3]  
Combined ratio 99.40% [4] 97.50% [4]  
Assets [Abstract]      
Reinsurance balance receivable, net 336,807   260,882
Prepaid reinsurance premiums 31,870   39,186
Reinsurance recoverable on unpaid losses 83,350   84,036
Deferred commissions and other acquisition expenses 102,342   88,482
Loan to related party 0   0
Goodwill and intangible assets, net 89,794   90,613
Restricted cash and cash equivalents and investments 1,032,818   1,029,537
Other assets 28,617   32,358
Total Assets - operating segments 1,705,598   1,625,094
Corporate assets 0   0
Total assets 1,705,598   1,625,094
AmTrust Quota Share Reinsurance Segment [Member]
      
Net Income (Loss) [Abstract]      
Net premiums written 419,010 344,818  
Net premiums earned 304,922 220,288  
Other insurance revenue 0 0  
Net loss and loss adjustment expenses (199,544) (145,645)  
Commission and other acquisition expenses (90,485) (65,132)  
General and administrative expenses (548) (489)  
Underwriting income (loss) 14,345 9,022  
Reconciliation to net income      
Net loss and loss adjustment expense ratio 65.40% [1] 66.10% [1]  
Commission and other acquisition expense ratio 29.70% [2] 29.60% [2]  
General and administrative expense ratio 0.20% [3] 0.20% [3]  
Combined ratio 95.30% [4] 95.90% [4]  
Assets [Abstract]      
Reinsurance balance receivable, net 338,412   278,573
Prepaid reinsurance premiums 0   0
Reinsurance recoverable on unpaid losses 0   0
Deferred commissions and other acquisition expenses 244,322   209,439
Loan to related party 167,975   167,975
Goodwill and intangible assets, net 0   0
Restricted cash and cash equivalents and investments 1,221,365   1,098,409
Other assets 0   0
Total Assets - operating segments 1,972,074   1,754,396
Corporate assets 0   0
Total assets 1,972,074   1,754,396
NGHC Quota Share Segment [Member]
      
Net Income (Loss) [Abstract]      
Net premiums written (737) 76,631  
Net premiums earned 14,992 71,905  
Other insurance revenue 0 0  
Net loss and loss adjustment expenses (10,436) (48,487)  
Commission and other acquisition expenses (4,756) (22,416)  
General and administrative expenses (199) (174)  
Underwriting income (loss) (399) 828  
Reconciliation to net income      
Net loss and loss adjustment expense ratio 69.60% [1] 67.40% [1]  
Commission and other acquisition expense ratio 31.70% [2] 31.20% [2]  
General and administrative expense ratio 1.40% [3] 0.20% [3]  
Combined ratio 102.70% [4] 98.80% [4]  
Assets [Abstract]      
Reinsurance balance receivable, net 0   20,690
Prepaid reinsurance premiums 0   0
Reinsurance recoverable on unpaid losses 0   0
Deferred commissions and other acquisition expenses 2,052   6,987
Loan to related party 0   0
Goodwill and intangible assets, net 0   0
Restricted cash and cash equivalents and investments 106,328   103,752
Other assets 0   0
Total Assets - operating segments 108,380   131,429
Corporate assets 0   0
Total assets $ 108,380   $ 131,429
[1] Calculated by dividing net loss and loss adjustment expenses by the sum of net premiums earned and other insurance revenue.
[2] Calculated by dividing commission and other acquisition expenses by the sum of net premiums earned and other insurance revenue.
[3] Calculated by dividing general and administrative expenses by the sum of net premiums earned and other insurance revenue.
[4] Calculated by adding together net loss and loss adjustment expense ratio, commission and other acquisition expense ratio and general and administrative expense ratio.