Loss Reserves - Reconciliation of Beginning and Ending Balances (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Loss Reserve [Roll Forward]
Reserve at beginning of period	$ 985,635	$ 1,438,813
Less reinsurance recoverable	48,474	50,493
Net reserve at beginning of period	937,161	1,388,320
Losses and LAE incurred in respect of delinquency notices received in:
Current year	59,070	80,416
Prior years	(35,220)	(52,797)
Total losses incurred	23,850	27,619
Losses and LAE paid in respect of delinquency notices received in:
Current year	95	331
Prior years	81,983	127,224
Reinsurance terminations	236	0
Total losses paid	82,314	127,555
Net reserve at end of period	878,697	1,288,384
Plus reinsurance recoverables	45,474	46,658
Reserve at end of period	$ 924,171	$ 1,335,042