Reinsurance - Allowance for Credit Loss on Reinsurance Recoverable (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Reinsurance Disclosures [Abstract]
Balance, beginning of period	$ 7,144	$ 3,917
Current period provision for expected credit losses	219	1,625
Balance, at the end of period	$ 7,363	$ 5,542