Investments in Fixed Maturity Securities (AFS Allowance for Credit Loss) (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2023	Mar. 31, 2022
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	$ 37,352	$ 22,238
Cumulative effect adjustment resulting from changes in accounting principles	37,142	26,153
Expected credit losses on securities for which credit losses were not previously recorded	186	484
Expected credit losses (gains) on securities for which credit losses were previously recorded	(391)	3,431
Reduction due to disposals	(5)	0
Allowance for expected credit losses, end of period	37,142	26,153
Foreign government
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	32,633	22,222
Cumulative effect adjustment resulting from changes in accounting principles	33,324	26,153
Expected credit losses on securities for which credit losses were not previously recorded	0	484
Expected credit losses (gains) on securities for which credit losses were previously recorded	691	3,447
Reduction due to disposals	0	0
Allowance for expected credit losses, end of period	33,324	26,153
Corporate
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	4,701	16
Cumulative effect adjustment resulting from changes in accounting principles	3,795	0
Expected credit losses on securities for which credit losses were not previously recorded	186	0
Expected credit losses (gains) on securities for which credit losses were previously recorded	(1,087)	(16)
Reduction due to disposals	(5)	0
Allowance for expected credit losses, end of period	3,795	$ 0
Mortgage-backed
Debt Securities, Available-for-sale, Allowance for Credit Loss [Roll Forward]
Allowance for expected credit losses, beginning of period	18
Cumulative effect adjustment resulting from changes in accounting principles	23
Expected credit losses on securities for which credit losses were not previously recorded	0
Expected credit losses (gains) on securities for which credit losses were previously recorded	5
Reduction due to disposals	0
Allowance for expected credit losses, end of period	$ 23

Amount of allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale).

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455

Reference 2: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 50
-Paragraph 9
-Subparagraph (i)
-URI http://asc.fasb.org/extlink&oid=124269663&loc=SL82922900-210455

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 320
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (aaa)
-URI http://asc.fasb.org/extlink&oid=123581744&loc=d3e27161-111563

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 326
-SubTopic 30
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=124258926&loc=SL82898722-210454

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Amount of expense for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), for which no credit loss was previously recorded.

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Amount of expense (reversal of expense) for allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale), not intended to be sold and not more likely than not will be required to sell before recovery of amortized cost basis, with previously recorded allowance.

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Amount of decrease in allowance for credit loss on investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) from sale.

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