Losses and LAE - Additional Disclosures: Cumulative Paid Claims / Reconciliation of Outstanding Liabilities (Details) - Mortgage insurance - USD ($) $ in Thousands	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	$ 1,886,986
Incurred losses, net of reinsurance	2,592,921
Mortgage
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Liabilities for claims, net of reinsurance	736,356
2012
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	708,929	$ 708,528	$ 704,770	$ 702,136	$ 692,291	$ 672,271	$ 631,982	$ 528,744	$ 295,332	$ 19,200
Incurred losses, net of reinsurance	713,057	713,146	713,839	713,750	714,783	715,646	720,502	711,213	763,969	$ 803,831
2013
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	395,292	395,093	392,818	388,688	379,036	357,087	307,361	191,040	34,504
Incurred losses, net of reinsurance	398,820	399,317	399,356	400,243	402,259	404,333	401,444	405,334	$ 505,732
2014
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	256,107	255,742	252,619	246,611	233,607	200,422	115,852	13,108
Incurred losses, net of reinsurance	260,254	261,377	261,507	260,098	264,620	265,891	247,074	$ 337,784
2015
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	175,874	174,812	172,645	163,916	142,421	84,271	10,479
Incurred losses, net of reinsurance	182,647	184,066	183,546	183,952	178,042	198,186	$ 222,555
2016
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	138,525	137,306	134,115	119,357	76,616	11,061
Incurred losses, net of reinsurance	148,349	148,640	148,811	149,753	165,440	$ 201,016
2017
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	111,458	108,484	99,678	66,585	24,653
Incurred losses, net of reinsurance	126,989	130,274	133,357	151,802	$ 180,851
2018
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	60,926	54,625	36,066	5,584
Incurred losses, net of reinsurance	88,252	95,534	116,634	$ 131,513
2019
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	28,896	18,703	4,220
Incurred losses, net of reinsurance	109,416	136,860	$ 143,475
2020
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	9,867	4,148
Incurred losses, net of reinsurance	408,809	$ 504,160
2021
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	1,112
Incurred losses, net of reinsurance	156,328
Short-duration Insurance Contracts, Accident Year Prior to 2011
Short-duration Insurance Contracts, Reconciliation of Claims Development to Liability [Line Items]
Cumulative paid claims, net of reinsurance	$ 30,421