Related Party Transactions - Schedule of AmTrust Quota Share Arrangement (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Related Party Transaction [Line Items]
Gross premiums written	$ 11,734	$ (561,139)
Net premiums earned	31,215	183,102
Net loss and loss adjustment expenses (loss and LAE)	(21,086)	(152,689)
Commission expenses	(11,973)	(69,617)
Quota Share Reinsurance Agreements | AmTrust Financial Services, Inc.
Related Party Transaction [Line Items]
Gross premiums written	0	(576,477)
Net premiums earned	18,684	158,130
Net loss and loss adjustment expenses (loss and LAE)	(14,045)	(137,944)
Commission expenses	(6,994)	(60,356)
Operating segments | AmTrust Reinsurance
Related Party Transaction [Line Items]
Gross premiums written	0	(576,477)
Net premiums earned	18,684	157,810
Net loss and loss adjustment expenses (loss and LAE)	(14,045)	(138,070)
Commission expenses	$ (6,994)	$ (60,356)