Losses and LAE - Additional Disclosures: Cumulative Paid Claims / Reconciliation of Outstanding Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Mortgage insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	$ 813,069
Incurred losses, net of reinsurance	1,125,893
Mortgage Insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liabilities for claims, net of reinsurance	329,204
Reinsurance Recoverable for Unpaid Claims and Claims Adjustments	25,074	$ 24,727	$ 66,676	$ 71,769
Mortgage Insurance | Mortgage insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liabilities for claims, net of reinsurance	329,204
2014 | Mortgage insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	256,185	255,981	256,107	255,742	$ 252,619	$ 246,611	$ 233,607	$ 200,422	$ 115,852	$ 13,108
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
2015 | Mortgage insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	177,237	176,823	175,874	174,812	172,645	163,916	142,421	84,271	10,479
Incurred losses, net of reinsurance	179,344	180,435	182,647	184,066	183,546	183,952	178,042	198,186	$ 222,555
2016 | Mortgage insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	139,651	139,539	138,525	137,306	134,115	119,357	76,616	11,061
Incurred losses, net of reinsurance	142,521	145,267	148,349	148,640	148,811	149,753	165,440	$ 201,016
2017 | Mortgage insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	113,027	112,445	111,458	108,484	99,678	66,585	24,653
Incurred losses, net of reinsurance	118,033	122,407	126,989	130,274	133,357	151,802	$ 180,851
2018 | Mortgage insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	63,603	62,968	60,926	54,625	36,066	5,584
Incurred losses, net of reinsurance	70,145	75,262	88,252	95,534	116,634	$ 131,513
2019 | Mortgage insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	37,960	35,594	28,896	18,703	4,220
Incurred losses, net of reinsurance	51,053	66,466	109,416	136,860	$ 143,475
2020 | Mortgage insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	17,884	14,635	9,867	4,148
Incurred losses, net of reinsurance	39,584	87,213	408,809	$ 504,160
2021 | Mortgage insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	4,409	2,561	1,112
Incurred losses, net of reinsurance	23,308	72,475	$ 156,328
2022 | Mortgage insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	2,867	498
Incurred losses, net of reinsurance	71,300	$ 155,908
2023 | Mortgage insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	246
Incurred losses, net of reinsurance	173,076
All outstanding liabilities before 2014, net of reinsurance | Mortgage insurance
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	$ 16,380