Losses and LAE - Mortgage Insurance Reserve for Losses and LAE Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022	Dec. 31, 2021
Loss reserve [Roll Forward]
Balance at beginning of period	$ 426,843
Deduct: Paid claims and LAE related to:
Balance at end of period	405,651
Mortgage
Loss reserve [Roll Forward]
Balance at beginning of period	420,955	$ 823,136
Less: Reinsurance recoverables	24,727	66,676
Balance at beginning of period, net of reinsurance recoverables	376,349	667,487	$ 396,228	$ 756,460
Add: Losses and LAE incurred in respect of default notices reported and unreported in:
Current year	50,579	40,662
Prior years	(67,442)	(124,897)
Total incurred	(16,863)	(84,235)
Deduct: Paid claims and LAE related to:
Current year	32	0
Prior years	2,984	4,738
Total paid	3,016	4,738
Balance at end of period, net of reinsurance recoverables	376,349	667,487
Add: Reinsurance recoverables	23,501	54,023
Balance at end of period	$ 399,850	$ 721,510