Loss Reserves (Details) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2023 USD ($) loan	Sep. 30, 2022 loan	Sep. 30, 2023 USD ($) loan	Sep. 30, 2022 USD ($) loan	Dec. 31, 2022 USD ($)
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Increase (decrease) in loss reserves | $			$ (32,460)	$ (280,152)
Losses incurred related to prior year notices | $			(148,948)	$ (327,512)
Premium refund liability, expected claim payments | $	$ 19,600		$ 19,600		$ 25,500
Primary Delinquent Inventory [Roll Forward]
Delinquent inventory at the beginning of period (in loans) | loan	23,823	26,855	26,387	33,290
New notices (in loans) | loan	12,240	10,990	34,117	31,089
Cures (in loans) | loan	(10,975)	(11,494)	(34,738)	(37,371)
Paid claims (in loans) | loan	(359)	(337)	(1,018)	(978)
Rescissions and denials (in loans) | loan	(9)	(11)	(28)	(27)
Other items removed from inventory (in loans) | loan	0	(125)	0	(125)
Delinquent inventory at end of period (in loans) | loan	24,720	25,878	24,720	25,878
$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 | $			$ 9,000
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 | $			15,000
Increase (decrease) in estimated claim rate on primary defaults
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Losses incurred related to prior year notices | $			(142,764)	$ (324,556)
Change in estimates related to severity on primary defaults, pool reserves, LAE reserves, reinsurance, and other
Causes of Increase (Decrease) in Liability for Unpaid Claims and Claims Adjustment Expense [Line Items]
Losses incurred related to prior year notices | $			$ (6,184)	$ (2,956)