Goodwill and Intangible Assets - Summary of Changes in Net Carrying Value of Intangible Assets (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Intangible Assets [Roll Forward]
Net Carrying Value	$ 37,537	$ 38,334
Amortization	(597)	(597)	$ (597)
Impairment Losses	0	(200)	0
Net Carrying Value	36,940	37,537	38,334
Excess and Surplus Lines
Intangible Assets [Roll Forward]
Net Carrying Value	30,565	30,927
Amortization	(362)	(362)	(362)
Impairment Losses	0	0
Net Carrying Value	30,203	30,565	30,927
Excess and Surplus Lines | Trademarks
Intangible Assets [Roll Forward]
Net Carrying Value	19,700	19,700
Amortization	0	0
Impairment Losses	0	0
Net Carrying Value	19,700	19,700	19,700
Excess and Surplus Lines | Insurance licenses and authorities
Intangible Assets [Roll Forward]
Net Carrying Value	4,900	4,900
Amortization	0	0
Impairment Losses	0	0
Net Carrying Value	4,900	4,900	4,900
Excess and Surplus Lines | Broker relationships
Intangible Assets [Roll Forward]
Net Carrying Value	5,965	6,327
Amortization	(362)	(362)
Impairment Losses	0	0
Net Carrying Value	5,603	5,965	6,327
Specialty Admitted Insurance
Intangible Assets [Roll Forward]
Net Carrying Value	6,972	7,407
Amortization	(235)	(235)	(235)
Impairment Losses	0	(200)
Net Carrying Value	6,737	6,972	7,407
Specialty Admitted Insurance | Trademarks
Intangible Assets [Roll Forward]
Net Carrying Value	2,500	2,500
Amortization	0	0
Impairment Losses	0	0
Net Carrying Value	2,500	2,500	2,500
Specialty Admitted Insurance | Insurance licenses and authorities
Intangible Assets [Roll Forward]
Net Carrying Value	4,065	4,265
Amortization	0	0
Impairment Losses	0	(200)
Net Carrying Value	4,065	4,065	4,265
Specialty Admitted Insurance | Broker relationships
Intangible Assets [Roll Forward]
Net Carrying Value	407	642
Amortization	(235)	(235)
Impairment Losses	0	0
Net Carrying Value	$ 172	$ 407	$ 642