Losses and LAE - Mortgage Insurance Loss Reserves Rollforward (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Loss reserve [Roll Forward]
Balance at beginning of year	$ 828,642
Deduct: Paid claims and LAE related to:
Balance at end of year	426,843	$ 828,642
Mortgage
Loss reserve [Roll Forward]
Balance at beginning of year	823,136	844,107	$ 401,273
Less: Reinsurance recoverables	66,676	71,769	14,594
Balance at beginning of year, net of reinsurance recoverable	396,228	756,460	772,338	$ 386,679
Add: Losses and LAE incurred in respect of default notices reported and unreported in:
Current year	160,049	160,565	517,807
Prior years	(499,423)	(141,126)	(34,547)
Total incurred	(339,374)	19,439	483,260
Deduct: Paid claims and LAE related to:
Current year	499	1,112	4,148
Prior years	20,359	34,205	93,453
Total paid	20,858	35,317	97,601
Balance at end of period, net of reinsurance recoverable	396,228	756,460	772,338
Add: reinsurance recoverables	24,727	66,676	71,769
Balance at end of year	$ 420,955	$ 823,136	$ 844,107