Loss Reserves (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2019 USD ($) loan	Mar. 31, 2018 USD ($) loan	Dec. 31, 2018 USD ($)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Percentage of prior year delinquent inventory resolved (as a percent)	32.00%	31.00%
Prior years	$ (8,425)	$ (35,220)
Claims paid upon commutation of coverage of pools	56,365	$ 81,983
Premium refund liability, expected claim payments	$ 37,000		$ 40,000
Primary Delinquent Inventory [Roll Forward]
Delinquent inventory at the beginning of period (in loans) | loan	32,898	46,556
New notices (in loans) | loan	13,611	14,623
Cures (in loans) | loan	(14,348)	(18,073)
Paids (including those charged to a deductible or captive) (in loans) | loan	(1,188)	(1,571)
Rescissions and denials (in loans) | loan	(52)	(68)
Other items removed from inventory (in loans) | loan	0	(224)
Delinquent inventory at end of period (in loans) | loan	30,921	41,243
Probable loss on litigation claims paying practices
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years	$ 23,500
Settlements for commutations of coverage, pools of nonperforming loans
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Claims paid upon commutation of coverage of pools		$ 7,000
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	(31,000)	(47,000)
Increase in estimated severity on primary defaults
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years	0	16,000
Change in estimates related to pool reserves, LAE reserves, reinsurance, and other
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years	$ 23,000	$ (4,000)