v3.8.0.1

Segment Information - Net Premiums (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums written	$ 617,330	$ 690,653	$ 2,201,950	$ 2,133,911
% of Total Net premiums written	100.00%	100.00%	100.00%	100.00%
Net premiums earned	$ 653,866	$ 698,278	$ 2,074,475	$ 1,951,851
% of Total Net premiums earned	100.00%	100.00%	100.00%	100.00%
Operating segments [Member] | Diversified Reinsurance segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums written	$ 207,137	$ 179,092	$ 671,880	$ 626,522
% of Total Net premiums written	33.60%	25.90%	30.50%	29.30%
Net premiums earned	$ 217,513	$ 175,141	$ 623,574	$ 538,152
% of Total Net premiums earned	33.30%	25.10%	30.10%	27.60%
Operating segments [Member] | AmTrust Reinsurance segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums written	$ 410,193	$ 511,561	$ 1,529,980	$ 1,507,389
% of Total Net premiums written	66.40%	74.10%	69.50%	70.70%
Net premiums earned	$ 436,353	$ 523,137	$ 1,450,811	$ 1,413,699
% of Total Net premiums earned	66.70%	74.90%	69.90%	72.40%
Operating segments [Member] | Property [Member] | Diversified Reinsurance segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums written	$ 37,962	$ 30,606	$ 132,398	$ 123,991
% of Total Net premiums written	6.20%	4.40%	6.00%	5.80%
Net premiums earned	$ 43,362	$ 29,921	$ 122,888	$ 103,023
% of Total Net premiums earned	6.60%	4.30%	5.90%	5.30%
Operating segments [Member] | Casualty [Member] | Diversified Reinsurance segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums written	$ 129,726	$ 115,360	$ 391,503	$ 365,332
% of Total Net premiums written	21.00%	16.70%	17.80%	17.10%
Net premiums earned	$ 130,428	$ 105,893	$ 375,141	$ 313,736
% of Total Net premiums earned	20.00%	15.20%	18.10%	16.10%
Operating segments [Member] | Accident and Health [Member] | Diversified Reinsurance segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums written	$ 16,946	$ 14,845	$ 74,504	$ 68,140
% of Total Net premiums written	2.70%	2.20%	3.40%	3.20%
Net premiums earned	$ 22,780	$ 18,436	$ 63,878	$ 55,788
% of Total Net premiums earned	3.50%	2.60%	3.10%	2.80%
Operating segments [Member] | International [Member] | Diversified Reinsurance segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums written	$ 22,503	$ 18,281	$ 73,475	$ 69,059
% of Total Net premiums written	3.70%	2.60%	3.30%	3.20%
Net premiums earned	$ 20,943	$ 20,891	$ 61,667	$ 65,605
% of Total Net premiums earned	3.20%	3.00%	3.00%	3.40%
Operating segments [Member] | Small Commercial Business [Member] | AmTrust Reinsurance segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums written	$ 295,499	$ 314,677	$ 1,028,905	$ 983,601
% of Total Net premiums written	47.90%	45.60%	46.70%	46.10%
Net premiums earned	$ 314,773	$ 320,596	$ 946,782	$ 864,699
% of Total Net premiums earned	48.10%	45.90%	45.60%	44.30%
Operating segments [Member] | Specialty Program [Member] | AmTrust Reinsurance segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums written	$ 63,816	$ 98,895	$ 255,767	$ 268,193
% of Total Net premiums written	10.30%	14.30%	11.60%	12.60%
Net premiums earned	$ 59,143	$ 89,856	$ 251,153	$ 251,543
% of Total Net premiums earned	9.10%	12.90%	12.10%	12.90%
Operating segments [Member] | Specialty Risk and Extended Warranty [Member] | AmTrust Reinsurance segment [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums written	$ 50,878	$ 97,989	$ 245,308	$ 255,595
% of Total Net premiums written	8.20%	14.20%	11.20%	12.00%
Net premiums earned	$ 62,437	$ 112,685	$ 252,876	$ 297,457
% of Total Net premiums earned	9.50%	16.10%	12.20%	15.20%
Other [Member]
Segment Reporting, Revenue Reconciling Item [Line Items]
Net premiums written	$ 0	$ 0	$ 90	$ 0
% of Total Net premiums written			0.00%	0.00%
Net premiums earned	$ 0	$ 0	$ 90	$ 0
% of Total Net premiums earned			0.00%	0.00%

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Amount, after premiums ceded to other entities and premiums assumed by the entity, of premiums earned.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 225
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-04.1)
-URI http://asc.fasb.org/extlink&oid=6879464&loc=d3e573970-122913

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 605
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=6486672&loc=d3e27261-158547

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
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-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-04.13(c))
-URI http://asc.fasb.org/extlink&oid=6879574&loc=d3e536633-122882

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 235
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-Paragraph 2
-Subparagraph (SX 210.12-17)
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