Loss Reserves (Details) $ in Thousands	3 Months Ended		6 Months Ended		12 Months Ended
	Jun. 30, 2016 USD ($) loan	Jun. 30, 2015 USD ($) loan	Jun. 30, 2016 USD ($) loan	Jun. 30, 2015 USD ($) loan	Dec. 31, 2015 USD ($) loan	Jun. 30, 2016 USD ($) loan	Dec. 31, 2015 USD ($) loan	Jun. 30, 2015 loan
Loss Reserve [Roll Forward]
Reserve at beginning of period			$ 1,893,402	$ 2,396,807	$ 2,396,807
Less reinsurance recoverable			44,487	57,841	57,841
Net reserve at beginning of period			1,848,915	2,338,966	2,338,966
Losses and LAE incurred in respect of defaults related to [Abstract]
Current year			196,543	223,564
Prior years			(64,941)	(51,541)
Subtotal			131,602	172,023
Losses and LAE paid in respect of defaults related to [Abstract]
Current year			1,396	2,382
Prior years			392,007	451,317
Reinsurance terminations			(4)	(15)
Subtotal			393,399	453,684
Net reserve at end of period	$ 1,587,118	$ 2,057,305	1,587,118	2,057,305	1,848,915
Plus reinsurance recoverables	45,215	53,456	45,215	53,456	44,487
Reserve at end of period	$ 1,632,333	$ 2,110,761	1,632,333	2,110,761	$ 1,893,402
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years			(64,941)	(51,541)
Prior years			$ 392,007	$ 451,317
Premium refund liability, expected claim payments						$ 97,000	$ 102,000
Primary Default Inventory [Roll Forward]
Default inventory at the beginning of period | loan	55,590	72,236	62,633	79,901	79,901
New notices | loan	16,080	17,451	32,811	36,347
Cures | loan	(15,640)	(17,897)	(34,693)	(39,664)
Paids (including those charged to a deductible or captive) | loan	(3,195)	(4,140)	(6,568)	(8,713)
Rescissions and denials | loan	(142)	(172)	(352)	(393)
Other items removed from inventory | loan	(135)	(1,121)	(1,273)	(1,121)
Default inventory at end of period | loan	52,558	66,357	52,558	66,357	62,633
Pool insurance notice inventory [Abstract]
Historical average period for uncured default to develop into paid claim			12 months
Aging of the Primary Default Inventory [Abstract]
3 months or less | loan						11,547	13,053	12,545
3 months or less (in hundredths)						22.00%	21.00%	19.00%
4 - 11 months | loan						12,680	15,763	15,487
4 - 11 months (in hundredths)						24.00%	25.00%	23.00%
12 months or more | loan						28,331	33,817	38,325
12 months or more (in hundredths)						54.00%	54.00%	58.00%
Total primary default inventory | loan	55,590	72,236	62,633	79,901	79,901	52,558	62,633	66,357
Total primary default inventory (in hundredths)						100.00%	100.00%	100.00%
Primary claims received inventory included in ending default inventory | loan						1,829	2,769	3,440
Primary claims received inventory included in ending default inventory (in hundredths)						3.00%	4.00%	5.00%
Percent of default inventory in default for more than 36 months			49.00%	51.00%	50.00%
Number of payments delinquent [Abstract]
3 payments or less | loan						17,299	20,360	19,274
3 payments or less (in hundredths)						33.00%	33.00%	29.00%
4 - 11 payments | loan						12,746	15,092	15,710
4 - 11 payments (in hundredths)						24.00%	24.00%	24.00%
12 payments or more | loan						22,513	27,181	31,373
12 payments or more (in hundredths)						43.00%	43.00%	47.00%
Total primary default inventory | loan	55,590	72,236	62,633	79,901	79,901	52,558	62,633	66,357
Total primary default inventory (in hundredths)						100.00%	100.00%	100.00%
Pool insurance notice inventory (in number of loans) | loan						2,024	2,739	3,129
Premium refund liability, expected future rescissions						$ 5,000	$ 7,000
Decrease in estimated claim rate on primary defaults
Losses and LAE incurred in respect of defaults related to [Abstract]
Prior years			$ (76,000)	$ (59,000)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years			$ (76,000)	$ (59,000)
Percentage of prior year default inventory resolved (in hundredths)			43.00%	41.00%
Increase in estimated severity on primary defaults
Losses and LAE incurred in respect of defaults related to [Abstract]
Prior years			$ 17,000	$ 15,000
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years			17,000	15,000
Change in estimates related to pool reserves, LAE reserves and reinsurance
Losses and LAE incurred in respect of defaults related to [Abstract]
Prior years			(6,000)	(8,000)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years			(6,000)	(8,000)
Change in estimates related to disputes on claims paying practices and IBNR
Losses and LAE incurred in respect of defaults related to [Abstract]
Prior years				20,000
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years				$ 20,000
Settlements For Claims Paying Practices And Nonperforming Loan Sale
Losses and LAE paid in respect of defaults related to [Abstract]
Prior years			51,000
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years			$ 51,000