Loss Reserves - Prior Year Loss Reserves (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Total prior year loss development	$ (404,130)	$ (60,015)	$ 19,604
(Decrease) in estimated claim rate on primary delinquencies
Liability for Claims and Claims Adjustment Expense [Line Items]
Total prior year loss development	(400,577)	(82,904)	(2,536)
Increase (decrease) in estimated claim severity on primary delinquencies
Liability for Claims and Claims Adjustment Expense [Line Items]
Total prior year loss development	(21,995)	310	13,535
Change in estimates related to pool reserves, LAE reserves, reinsurance and other
Liability for Claims and Claims Adjustment Expense [Line Items]
Total prior year loss development	$ 18,442	$ 22,579	$ 8,605