Loss Reserves - Reconciliation of Changes in Loss Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Loss Reserve [Roll Forward]
Reserve at beginning of year	$ 883,522	$ 880,537	$ 555,334
Less reinsurance recoverable	28,240	66,905	95,042	$ 21,641
Net reserve at beginning of year	529,748	816,617	785,495	$ 533,693
Losses incurred: [Abstract]
Current year	149,565	124,592	345,170
Prior years	(404,130)	(60,015)	19,604
Total losses incurred	(254,565)	64,577	364,774
Losses paid [Abstract]
Current year	362	664	3,069
Prior years	49,626	68,769	109,923
Reinsurance terminations	(17,684)	(35,978)	(20)
Total losses paid	32,304	33,455	112,972
Net reserve at end of year	529,748	816,617	785,495
Reserve at end of year	$ 557,988	$ 883,522	$ 880,537