v2.4.0.8
Segments - Net Premiums (Details) (USD $)
In Thousands, unless otherwise specified
3 Months Ended 9 Months Ended
Sep. 30, 2013
Sep. 30, 2012
Sep. 30, 2013
Sep. 30, 2012
Segment Reporting Information [Line Items]        
Net premiums written $ 463,418 $ 455,847 $ 1,650,426 $ 1,458,640
% of Total Net premiums written 100.00% 100.00% 100.00% 100.00%
Net premiums earned 508,126 448,973 1,509,841 1,324,585
% of Total Net premiums earned 100.00% 100.00% 100.00% 100.00%
Diversified Reinsurance Segment [Member]
       
Segment Reporting Information [Line Items]        
Net premiums written 185,620 193,943 588,164 626,220
% of Total Net premiums written 40.10% 42.50% 35.60% 42.90%
Net premiums earned 198,966 200,020 573,551 603,613
% of Total Net premiums earned 39.20% 44.50% 37.90% 45.60%
AmTrust Quota Share Reinsurance Segment [Member]
       
Segment Reporting Information [Line Items]        
Net premiums written 259,633 186,258 895,029 607,902
% of Total Net premiums written 56.00% 40.90% 54.30% 41.70%
Net premiums earned 243,408 177,293 725,100 512,988
% of Total Net premiums earned 47.90% 39.50% 48.10% 38.70%
NGHC Quota Share Segment [Member]
       
Segment Reporting Information [Line Items]        
Net premiums written 18,165 75,646 167,233 224,518
% of Total Net premiums written 3.90% 16.60% 10.10% 15.40%
Net premiums earned 65,752 71,660 211,190 207,984
% of Total Net premiums earned 12.90% 16.00% 14.00% 15.70%
Property [Member] | Diversified Reinsurance Segment [Member]
       
Segment Reporting Information [Line Items]        
Net premiums written 26,783 41,667 112,861 157,628
% of Total Net premiums written 5.80% 9.10% 6.80% 10.80%
Net premiums earned 41,652 50,688 116,970 164,739
% of Total Net premiums earned 8.20% 11.30% 7.70% 12.40%
Casualty [Member] | Diversified Reinsurance Segment [Member]
       
Segment Reporting Information [Line Items]        
Net premiums written 122,600 114,655 359,816 349,356
% of Total Net premiums written 26.40% 25.20% 21.80% 24.00%
Net premiums earned 126,091 119,572 359,988 334,559
% of Total Net premiums earned 24.80% 26.60% 23.80% 25.30%
Accident and Health [Member] | Diversified Reinsurance Segment [Member]
       
Segment Reporting Information [Line Items]        
Net premiums written 9,040 9,174 31,649 34,484
% of Total Net premiums written 2.00% 2.00% 1.90% 2.30%
Net premiums earned 8,994 11,176 27,356 32,547
% of Total Net premiums earned 1.80% 2.50% 1.80% 2.50%
International [Member] | Diversified Reinsurance Segment [Member]
       
Segment Reporting Information [Line Items]        
Net premiums written 27,197 28,447 83,838 84,752
% of Total Net premiums written 5.90% 6.20% 5.10% 5.80%
Net premiums earned 22,229 18,584 69,237 71,768
% of Total Net premiums earned 4.40% 4.10% 4.60% 5.40%
Small Commercial Business [Member] | AmTrust Quota Share Reinsurance Segment [Member]
       
Segment Reporting Information [Line Items]        
Net premiums written 136,725 84,024 434,951 256,198
% of Total Net premiums written 29.50% 18.40% 26.40% 17.60%
Net premiums earned 130,472 81,287 350,295 218,086
% of Total Net premiums earned 25.70% 18.10% 23.20% 16.40%
Specialty Program [Member] | AmTrust Quota Share Reinsurance Segment [Member]
       
Segment Reporting Information [Line Items]        
Net premiums written 41,698 14,931 115,313 63,877
% of Total Net premiums written 9.00% 3.30% 7.00% 4.40%
Net premiums earned 39,661 9,828 105,122 60,414
% of Total Net premiums earned 7.80% 2.20% 7.00% 4.60%
Specialty Risk and Extended Warranty [Member] | AmTrust Quota Share Reinsurance Segment [Member]
       
Segment Reporting Information [Line Items]        
Net premiums written 81,210 87,303 344,765 287,827
% of Total Net premiums written 17.50% 19.20% 20.90% 19.70%
Net premiums earned 73,275 86,178 269,683 234,488
% of Total Net premiums earned 14.40% 19.20% 17.90% 17.70%
Automobile Liability [Member] | NGHC Quota Share Segment [Member]
       
Segment Reporting Information [Line Items]        
Net premiums written 9,707 39,019 95,631 118,288
% of Total Net premiums written 2.10% 8.60% 5.80% 8.10%
Net premiums earned 38,015 38,374 122,118 113,168
% of Total Net premiums earned 7.50% 8.60% 8.10% 8.50%
Automobile Physical Damage [Member] | NGHC Quota Share Segment [Member]
       
Segment Reporting Information [Line Items]        
Net premiums written 8,458 36,627 71,602 106,230
% of Total Net premiums written 1.80% 8.00% 4.30% 7.30%
Net premiums earned $ 27,737 $ 33,286 $ 89,072 $ 94,816
% of Total Net premiums earned 5.40% 7.40% 5.90% 7.20%