Segment Information - Underwriting Results and Reconciliation from Reportable Segments and Other's Category Net Income (Loss) to Consolidated (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020 USD ($)	Jun. 30, 2019 USD ($)	Jun. 30, 2020 USD ($) Segment	Jun. 30, 2019 USD ($)	Dec. 31, 2019 USD ($)
Segment Reporting Information [Line Items]
Number of reporting segments | Segment			2
Net Income (Loss) [Abstract]
Gross premiums written	$ 4,982	$ 2,117	$ 16,716	$ (559,022)
Net premiums written	4,090	(409)	14,462	(561,939)
Net premiums earned	21,308	133,986	52,523	317,088
Other insurance revenue	250	754	658	1,566
Net loss and loss adjustment expenses (loss and LAE)	(11,008)	(121,561)	(32,094)	(274,250)
Commission and other acquisition expenses	(8,154)	(49,656)	(20,127)	(119,273)
General and administrative expenses	(2,413)	(2,654)	(4,670)	(6,951)
Underwriting income (loss)	(17)	(39,131)	(3,710)	(81,820)
Reconciliation to net income (loss) from continuing operations
Net investment income and realized gains on investment	23,184	55,208	52,186	76,129
Total other-than-temporary impairment losses	0	0	(1,506)	0
Interest and amortization expenses	(4,830)	(4,830)	(9,661)	(9,659)
Foreign exchange and other gains (losses), net	(2,295)	1,207	5,902	6,186
Other general and administrative expenses	(6,848)	(9,504)	(13,141)	(21,826)
Income tax benefit	18	1,026	3	1,064
Income (loss) from continuing operations	$ 9,212	$ 3,976	$ 30,073	$ (29,926)
Net loss and LAE ratio	51.00%	90.20%	60.40%	86.10%
Commission and other acquisition expense ratio	37.80%	36.90%	37.80%	37.40%
General and administrative expense ratio	43.00%	9.00%	33.50%	9.00%
Expense ratio	80.80%	45.90%	71.30%	46.40%
Combined ratio	131.80%	136.10%	131.70%	132.50%
Assets [Abstract]
Assets	$ 3,213,436		$ 3,213,436		$ 3,568,196
Operating Segments
Assets [Abstract]
Assets	2,728,040		2,728,040		3,011,647
Operating Segments | Diversified Reinsurance
Net Income (Loss) [Abstract]
Gross premiums written	9,687	$ 11,244	21,421	$ 26,582
Net premiums written	8,553	8,718	18,925	23,665
Net premiums earned	11,527	22,472	24,058	47,764
Other insurance revenue	250	754	658	1,566
Net loss and loss adjustment expenses (loss and LAE)	(6,038)	(12,497)	(13,079)	(26,888)
Commission and other acquisition expenses	(4,374)	(8,147)	(9,353)	(17,408)
General and administrative expenses	(1,746)	(2,092)	(3,359)	(5,123)
Underwriting income (loss)	$ (381)	$ 490	$ (1,075)	$ (89)
Reconciliation to net income (loss) from continuing operations
Net loss and LAE ratio	51.30%	53.80%	52.90%	54.50%
Commission and other acquisition expense ratio	37.10%	35.10%	37.80%	35.30%
General and administrative expense ratio	14.80%	9.00%	13.60%	10.40%
Expense ratio	51.90%	44.10%	51.40%	45.70%
Combined ratio	103.20%	97.90%	104.30%	100.20%
Assets [Abstract]
Assets	$ 157,302		$ 157,302		167,845
Operating Segments | AmTrust Reinsurance
Net Income (Loss) [Abstract]
Gross premiums written	(4,705)	$ (9,127)	(4,705)	$ (585,604)
Net premiums written	(4,463)	(9,127)	(4,463)	(585,604)
Net premiums earned	9,781	111,514	28,465	269,324
Other insurance revenue	0	0	0	0
Net loss and loss adjustment expenses (loss and LAE)	(4,970)	(109,088)	(19,015)	(247,158)
Commission and other acquisition expenses	(3,780)	(41,509)	(10,774)	(101,865)
General and administrative expenses	(667)	(562)	(1,311)	(1,828)
Underwriting income (loss)	$ 364	$ (39,645)	$ (2,635)	$ (81,527)
Reconciliation to net income (loss) from continuing operations
Net loss and LAE ratio	50.80%	97.80%	66.80%	91.80%
Commission and other acquisition expense ratio	38.60%	37.20%	37.80%	37.80%
General and administrative expense ratio	6.90%	0.50%	4.70%	0.70%
Expense ratio	45.50%	37.70%	42.50%	38.50%
Combined ratio	96.30%	135.50%	109.30%	130.30%
Assets [Abstract]
Assets	$ 2,570,738		$ 2,570,738		2,843,802
Other
Net Income (Loss) [Abstract]
Gross premiums written		$ 0		$ 0
Net premiums written		0		0
Net premiums earned		0		0
Other insurance revenue		0		0
Net loss and loss adjustment expenses (loss and LAE)		24		(204)
Commission and other acquisition expenses		0		0
General and administrative expenses		0		0
Underwriting income (loss)		$ 24		$ (204)
Assets [Abstract]
Assets	485,396		485,396		556,549
Other | Diversified Reinsurance
Assets [Abstract]
Assets	0		0		0
Other | AmTrust Reinsurance
Assets [Abstract]
Assets	$ 0		$ 0		$ 0