Short Duration Contracts - Claims development - Mortgage (Details) $ in Thousands	Dec. 31, 2022 USD ($) claims	Dec. 31, 2021 USD ($)	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]
Liabilities for losses and loss adjustment expenses, net of reinsurance	$ 13,445,271
Mortgage
Claims Development [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	1,543,256
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	1,156,723
All outstanding liabilities before 2012, net of reinsurance	10,585
Liabilities for losses and loss adjustment expenses, net of reinsurance	397,118
Mortgage | 2013
Claims Development [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	390,299	$ 391,324	$ 391,062	$ 390,987	$ 393,149	$ 395,693	$ 405,809	$ 411,793	$ 419,668	$ 469,311
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	388,036	387,879	387,894	386,853	382,200	373,909	353,189	308,956	203,957	$ 41,447
Total of IBNR liabilities plus expected development on reported claims	$ 2
Cumulative number of paid claims | claims	9,474
Mortgage | 2014
Claims Development [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 260,554	262,829	262,682	261,091	265,992	266,027	279,434	297,151	316,095
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	257,232	256,875	256,285	254,175	247,038	233,879	201,925	129,159	$ 20,099
Total of IBNR liabilities plus expected development on reported claims	$ 4
Cumulative number of paid claims | claims	6,311
Mortgage | 2015
Claims Development [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 188,649	190,560	190,913	189,235	194,677	198,001	197,238	222,790
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	184,955	184,025	183,472	180,321	171,337	151,222	92,431	$ 16,159
Total of IBNR liabilities plus expected development on reported claims	$ 1
Cumulative number of paid claims | claims	4,573
Mortgage | 2016
Claims Development [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 137,415	141,657	142,392	140,608	148,715	170,532	183,556
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	132,387	131,717	131,161	127,286	113,357	72,201	$ 11,462
Total of IBNR liabilities plus expected development on reported claims	$ 0
Cumulative number of paid claims | claims	3,445
Mortgage | 2017
Claims Development [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 102,005	109,242	108,181	107,255	132,220	179,376
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	91,645	89,756	87,317	78,650	48,112	$ 8,622
Total of IBNR liabilities plus expected development on reported claims	$ (1)
Cumulative number of paid claims | claims	2,516
Mortgage | 2018
Claims Development [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 71,976	87,962	89,120	96,357	132,318
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	58,687	55,853	50,135	31,478	$ 3,966
Total of IBNR liabilities plus expected development on reported claims	$ (4)
Cumulative number of paid claims | claims	1,718
Mortgage | 2019
Claims Development [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 63,485	110,362	119,253	108,424
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	34,178	29,102	20,105	$ 2,899
Total of IBNR liabilities plus expected development on reported claims	$ 74
Cumulative number of paid claims | claims	1,002
Mortgage | 2020
Claims Development [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 78,334	373,533	420,003
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	7,740	4,144	$ 1,040
Total of IBNR liabilities plus expected development on reported claims	$ 476
Cumulative number of paid claims | claims	299
Mortgage | 2021
Claims Development [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 77,212	144,375
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	1,687	$ 469
Total of IBNR liabilities plus expected development on reported claims	$ 379
Cumulative number of paid claims | claims	72
Mortgage | 2022
Claims Development [Line Items]
Incurred losses and allocated loss adjustment expenses, net of reinsurance	$ 173,327
Cumulative paid losses and allocated loss adjustment expenses, net of reinsurance	176
Total of IBNR liabilities plus expected development on reported claims	$ 2,147
Cumulative number of paid claims | claims	7