Losses and LAE - Additional Disclosures: Claims Development (Details) - Mortgage insurance $ in Thousands	Dec. 31, 2023 USD ($) default	Dec. 31, 2022 USD ($)	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 ($)	Dec. 31, 2014 USD ($)
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 1,125,893
2014
Claims Development [Line Items]
Incurred losses, net of reinsurance	257,529	$ 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	$ 3
Cumulative Number of Reported Defaults | default	47,976
2015
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 179,344	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	$ 5
Cumulative Number of Reported Defaults | default	42,607
2016
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 142,521	145,267	148,349	148,640	148,811	149,753	165,440	$ 201,016
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 7
Cumulative Number of Reported Defaults | default	40,503
2017
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 118,033	122,407	126,989	130,274	133,357	151,802	$ 180,851
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 12
Cumulative Number of Reported Defaults | default	42,888
2018
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 70,145	75,262	88,252	95,534	116,634	$ 131,513
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 16
Cumulative Number of Reported Defaults | default	37,369
2019
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 51,053	66,466	109,416	136,860	$ 143,475
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 33
Cumulative Number of Reported Defaults | default	40,985
2020
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 39,584	87,213	408,809	$ 504,160
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 55
Cumulative Number of Reported Defaults | default	108,025
2021
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 23,308	72,475	$ 156,328
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 48
Cumulative Number of Reported Defaults | default	37,470
2022
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 71,300	$ 155,908
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 176
Cumulative Number of Reported Defaults | default	37,738
2023
Claims Development [Line Items]
Incurred losses, net of reinsurance	$ 173,076
Total of IBNR Liabilities Plus Expected Development on Reported Claims	$ 1,425
Cumulative Number of Reported Defaults | default	44,007