Loss Reserves (Details) $ in Thousands	3 Months Ended
	Mar. 31, 2022 USD ($) loan	Mar. 31, 2021 USD ($) loan	Dec. 31, 2021 USD ($)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Increase (decrease) in loss reserves	$ (32,250)	$ 32,573
Prior years	(55,658)	(1,789)
Prior years	10,748	$ 14,922
Premium refund liability, expected claim payments	$ 36,400		$ 37,300
Primary Delinquent Inventory [Roll Forward]
Delinquent inventory at the beginning of period (in loans) | loan	33,290	57,710
New notices (in loans) | loan	10,703	13,011
Cures (in loans) | loan	(13,200)	(17,628)
Paids (including those charged to a deductible or captive) (in loans) | loan	(322)	(312)
Rescissions and denials (in loans) | loan	(9)	(6)
Delinquent inventory at end of period (in loans) | loan	30,462	52,775
$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	$ 15,000
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	18,000
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	(55,777)	$ 87
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	(2,172)	59
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	$ 2,291	$ (1,935)