Losses and LAE - Mortgage Insurance Reserve for Losses and LAE Rollforward (Details) - USD ($) $ in Thousands	9 Months Ended
	Sep. 30, 2022	Sep. 30, 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	483,664
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	448,091	813,284	$ 756,460	$ 772,338
Add: Losses and LAE incurred in respect of default notices reported and unreported in:
Current year	115,159	119,823
Prior years	(411,024)	(53,947)
Total incurred	(295,865)	65,876
Deduct: Paid claims and LAE related to:
Current year	381	499
Prior years	12,123	24,431
Total paid	12,504	24,930
Balance at end of period, net of reinsurance recoverables	448,091	813,284
Add: Reinsurance recoverables	29,656	74,737
Balance at end of period	$ 477,747	$ 888,021