Losses and LAE - Reserve for Losses and LAE by Segment (Details) - USD ($) $ in Thousands	Sep. 30, 2022	Dec. 31, 2021	Sep. 30, 2021	Dec. 31, 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Total reserve for losses and LAE	$ 483,664	$ 828,642
Mortgage insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Total reserve for losses and LAE	477,747	823,136	$ 888,021	$ 844,107
Mortgage insurance | Primary case
Liability for Claims and Claims Adjustment Expense [Line Items]
Total reserve for losses and LAE	454,726	790,380
Mortgage insurance | Primary IBNR and LAE
Liability for Claims and Claims Adjustment Expense [Line Items]
Total reserve for losses and LAE	13,672	22,745
Mortgage insurance | Pool and other
Liability for Claims and Claims Adjustment Expense [Line Items]
Total reserve for losses and LAE	9,349	10,011
Title insurance
Liability for Claims and Claims Adjustment Expense [Line Items]
Total reserve for losses and LAE	$ 5,917	$ 5,506