Investments - Composition of Current and Past Due Mortgage Loans on Real Estate (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023
Loans and Leases Receivable Disclosure [Line Items]
Allowance for credit losses	$ (115)	$ (114)
Unamortized premium (discount)	41	36
Mark-to-market gains (losses)	(37)	(37)
Total carrying value	19,176	18,873
Current
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	19,115	18,830
30 to 59 days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	41	89
60 to 89 days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	12	9
90 or more days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	119	60
Commercial
Loans and Leases Receivable Disclosure [Line Items]
Allowance for credit losses	(84)	(86)
Unamortized premium (discount)	(7)	(7)
Mark-to-market gains (losses)	(38)	(36)
Total carrying value	17,219	17,097
Commercial \| Current
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	17,282	17,165
Commercial \| 30 to 59 days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	4	61
Commercial \| 60 to 89 days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	2	0
Commercial \| 90 or more days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	60	0
Residential
Loans and Leases Receivable Disclosure [Line Items]
Allowance for credit losses	(31)	(28)
Unamortized premium (discount)	48	43
Mark-to-market gains (losses)	1	(1)
Total carrying value	1,957	1,776
Residential \| Current
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	1,833	1,665
Residential \| 30 to 59 days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	37	28
Residential \| 60 to 89 days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	10	9
Residential \| 90 or more days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	$ 59	$ 60

This item represents the difference between the aggregate fair value and the aggregate unpaid principal balance of loans and long-term receivables (other than securities categorized as trading, available-for-sale or held-to-maturity) that have contractual principal amounts and for which the fair value option has been elected.

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