Losses and LAE - Reserve for Losses and LAE by Segment (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for losses and loss adjustment expense	$ 727,247	$ 828,642
Mortgage insurance loss reserves
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for losses and loss adjustment expense	721,510	823,136	$ 882,838	$ 844,107
Title insurance loss reserves
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for losses and loss adjustment expense	5,737	5,506
First Lien Mortgage Insurance Products | Mortgage insurance loss reserves | Primary Case Reserves
Liability for Claims and Claims Adjustment Expense [Line Items]
Reserve for losses and loss adjustment expense	$ 691,100	$ 790,400