Loss Reserves - Narrative (Details) $ in Thousands	3 Months Ended	12 Months Ended
	Dec. 31, 2017 loan	Dec. 31, 2019 USD ($) Payment loan	Dec. 31, 2018 USD ($) loan	Dec. 31, 2017 USD ($) loan
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Minimum number of payments past due to be in default | Payment		2
Premium refund liability, expected claim payments | $		$ 30,000	$ 40,000
Percentage of prior year default inventory resolved (in hundredths)		69.00%	73.00%	67.00%
Other items removed from inventory | loan		639	1,578	1,337
Losses for unpaid claims and adjustment expense | $		$ 235,551	$ 327,743	$ 493,300
Default notices for loans in IADAs | loan	9,294
Default inventory in FEMA individual assistance disaster areas | loan	12,446			12,446
Percent of inventory in default for more than 36 consecutive months	45.00%	36.00%	38.00%	45.00%
Pool insurance notice inventory (in number of loans) | loan	1,309	653	859	1,309
Settlements for commutations of coverage, pools of nonperforming loans
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Losses for unpaid claims and adjustment expense | $		$ 30,000	$ 50,000	$ 54,000
Settlements for claims paying practices
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Losses for unpaid claims and adjustment expense | $		$ 23,500