Loss Reserves (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2017 USD ($) loan	Mar. 31, 2016 USD ($) loan	Dec. 31, 2016 USD ($)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years | $	$ (52,797)	$ (7,467)
Prior years | $	$ 127,224	$ 221,457
Other items removed from inventory (in loans)	(14)	(1,138)
Premium refund liability, expected claim payments | $	$ 81,000		$ 85,000
Primary Default Inventory [Roll Forward]
Default inventory at the beginning of period (in loans)	50,282	62,633
New notices (in loans)	14,939	16,731
Cures (in loans)	(17,128)	(19,053)
Paids (including those charged to a deductible or captive) (in loans)	(2,635)	(3,373)
Rescissions and denials (in loans)	(95)	(210)
Other items removed from inventory (in loans)	(14)	(1,138)
Default inventory at end of period (in loans)	45,349	55,590
Decrease in estimated claim rate on primary defaults
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years | $	$ (54,000)	$ (26,000)
Percentage of prior year default inventory resolved (as a percent)	29.00%	28.00%
Increase in estimated severity on primary defaults
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years | $	$ 4,000	$ 22,000
Change in estimates related to pool reserves, LAE reserves and reinsurance
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years | $	$ (3,000)	(3,000)
Settlements for claims paying practices and nonperforming loan sale
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years | $		$ 47,000