Loss Reserves - Reconciliation of Beginning and Ending Balances (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019
Loss Reserve [Roll Forward]
Reserve at beginning of period	$ 555,334	$ 674,019
Less reinsurance recoverable	21,641	33,328
Net reserve at beginning of period	533,693	640,691
Losses and LAE incurred in respect of delinquency notices received in:
Current year	265,546	94,063
Prior years	12,784	(33,164)
Total losses incurred	278,330	60,899
Losses and LAE paid in respect of delinquency notices received in:
Current year	271	2,650
Prior years	77,820	109,420
Reinsurance terminations	(20)	(13,980)
Total losses paid	78,071	98,090
Net reserve at end of period	733,952	603,500
Plus reinsurance recoverables	63,444	18,402
Reserve at end of period	$ 797,396	$ 621,902