Investments in Fixed Maturity Securities (AFS Allowance for Credit Loss) (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	$ 21,837	$ 44,248	$ 36,708	$ 37,352
Change on securities for which credit losses were not previously recorded	47	2,482	2,048	4,973
Change on securities for which credit losses were previously recorded	(14,552)	(366)	(30,863)	4,046
Reduction due to disposals	(379)	0	(940)	(7)
Balance, end of period	6,953	46,364	6,953	46,364
Foreign government
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	19,469	33,052	29,603	32,633
Change on securities for which credit losses were not previously recorded	47	0	347	0
Change on securities for which credit losses were previously recorded	(12,782)	3,119	(23,216)	3,538
Reduction due to disposals	(379)	0	(379)	0
Balance, end of period	6,355	36,171	6,355	36,171
Corporate
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	0	8,867	5,026	4,701
Change on securities for which credit losses were not previously recorded	0	756	0	942
Change on securities for which credit losses were previously recorded	0	(3,853)	(5,026)	134
Reduction due to disposals	0	0	0	(7)
Balance, end of period	0	5,770	0	5,770
Mortgage-backed
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	1,140	885	158	18
Change on securities for which credit losses were not previously recorded	0	905	1,701	1,766
Change on securities for which credit losses were previously recorded	(1,088)	310	(1,246)	316
Reduction due to disposals	0	0	(561)	0
Balance, end of period	52	2,100	52	2,100
Asset-backed
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	889	1,444	1,164	0
Change on securities for which credit losses were not previously recorded	0	0	0	1,444
Change on securities for which credit losses were previously recorded	(343)	58	(618)	58
Reduction due to disposals	0	0	0	0
Balance, end of period	546	1,502	546	1,502
State and municipal
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Balance, beginning of period	339	0	757	0
Change on securities for which credit losses were not previously recorded	0	821	0	821
Change on securities for which credit losses were previously recorded	(339)	0	(757)	0
Reduction due to disposals	0	0	0	0
Balance, end of period	$ 0	$ 821	$ 0	$ 821