Losses and LAE - Additional Disclosures: Claims Development (Details) - Mortgage insurance $ in Thousands	Dec. 31, 2022 USD ($) default	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)	Dec. 31, 2016 USD ($)	Dec. 31, 2015 USD ($)	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 1,560,413
2013
Claims Development [Line Items]
Incurred losses, net of reinsurance	397,207	$ 398,820	$ 399,317	$ 399,356	$ 400,243	$ 402,259	$ 404,333	$ 401,444	$ 405,334	$ 505,732
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 5
Cumulative Number of Reported Defaults | default	58,577
2014
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 257,773	260,254	261,377	261,507	260,098	264,620	265,891	247,074	$ 337,784
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 6
Cumulative Number of Reported Defaults | default	47,976
2015
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 180,435	182,647	184,066	183,546	183,952	178,042	198,186	$ 222,555
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 9
Cumulative Number of Reported Defaults | default	42,607
2016
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 145,267	148,349	148,640	148,811	149,753	165,440	$ 201,016
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 14
Cumulative Number of Reported Defaults | default	40,503
2017
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 122,407	126,989	130,274	133,357	151,802	$ 180,851
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 25
Cumulative Number of Reported Defaults | default	42,888
2018
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 75,262	88,252	95,534	116,634	$ 131,513
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 32
Cumulative Number of Reported Defaults | default	37,369
2019
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 66,466	109,416	136,860	$ 143,475
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 79
Cumulative Number of Reported Defaults | default	40,985
2020
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 87,213	408,809	$ 504,160
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 193
Cumulative Number of Reported Defaults | default	108,025
2021
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 72,475	$ 156,328
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 184
Cumulative Number of Reported Defaults | default	37,470
2022
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 155,908
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 1,550
Cumulative Number of Reported Defaults | default	37,738