Loss Reserves (Details) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2021 USD ($) loan	Jun. 30, 2020 loan	Jun. 30, 2021 USD ($) loan	Jun. 30, 2020 USD ($) loan	Dec. 31, 2020 USD ($)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Increase (decrease) in loss reserves			$ 55,699	$ 242,062
Prior years			1,732	$ 12,784
Premium refund liability, expected claim payments	$ 32,600		$ 32,600		$ 30,100
Primary Delinquent Inventory [Roll Forward]
Delinquent inventory at the beginning of period (in loans) | loan	52,775	27,384	57,710	30,028
New notices (in loans) | loan	9,036	57,584	22,047	69,982
Cures (in loans) | loan	(18,460)	(14,964)	(36,088)	(29,077)
Paids (including those charged to a deductible or captive) (in loans) | loan	(346)	(661)	(658)	(1,558)
Rescissions and denials (in loans) | loan	(6)	(17)	(12)	(49)
Delinquent inventory at end of period (in loans) | loan	42,999	69,326	42,999	69,326
$1,000 Increase/Decrease In Average Severity Reserve Factor
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Increase (decrease) in loss reserves			$ 17,000
One Percentage Point Increase/Decrease In Average Claim Rate Reserve Factor
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Increase (decrease) in loss reserves			25,000
Change in estimates related to IBNR reserves
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Increase (decrease) in loss reserves			(5,900)	$ 38,900
Probable loss on litigation claims paying practices
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years			6,300
Increase (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			(356)	(2,104)
Increase (decrease) in estimated severity on primary defaults
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Prior years			512	13,767
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			$ 1,576	$ 1,121