Losses and LAE - Mortgage Insurance Reserve for Losses and LAE Rollforward (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021	Dec. 31, 2020
Loss reserve [Roll Forward]
Balance at beginning of period	$ 828,642
Deduct: Paid claims and LAE related to:
Balance at end of period	727,247
Mortgage
Loss reserve [Roll Forward]
Balance at beginning of period	823,136	$ 844,107
Less: Reinsurance recoverables	66,676	71,769
Balance at beginning of period, net of reinsurance recoverables	667,487	807,664	$ 756,460	$ 772,338
Add: Losses and LAE incurred in respect of default notices reported and unreported in:
Current year	40,662	50,312
Prior years	(124,897)	(4,513)
Total incurred	(84,235)	45,799
Deduct: Paid claims and LAE related to:
Current year	0	16
Prior years	4,738	10,457
Total paid	4,738	10,473
Balance at end of period, net of reinsurance recoverables	667,487	807,664
Add: Reinsurance recoverables	54,023	75,174
Balance at end of period	$ 721,510	$ 882,838