Loss Reserves - Reconciliation of Beginning and Ending Balances (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2018	Sep. 30, 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	155,808	219,485
Prior years	(146,931)	(134,780)
Total losses incurred	8,877	84,705
Losses and LAE paid in respect of delinquency notices received in:
Current year	2,449	5,474
Prior years	257,808	407,977
Reinsurance terminations	(1,984)	301
Total losses paid	258,273	413,752
Net reserve at end of period	687,765	1,059,273
Plus reinsurance recoverables	33,281	45,878
Reserve at end of period	$ 721,046	$ 1,105,151