Reserve for Losses and Loss Adjustment Expenses - Narrative (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Mar. 31, 2020
Liability for Claims and Claims Adjustment Expense [Abstract]
Allowance for uncollectible reinsurance balances	$ 335		$ 335		$ 335
Favorable development on prior year loss reserves
Reserve for losses and loss adjustment expenses	(1,126)	$ (2,315)	(2,000)	$ (3,283)
Excess and Surplus Lines
Favorable development on prior year loss reserves
Reserve for losses and loss adjustment expenses	2,800	(1,200)	2,900	(1,200)
Specialty Admitted Insurance
Favorable development on prior year loss reserves
Reserve for losses and loss adjustment expenses	1,000	1,200	2,000	3,300
Casualty Reinsurance
Favorable development on prior year loss reserves
Reserve for losses and loss adjustment expenses	$ (5,000)	$ (2,400)	$ (6,900)	$ (5,300)