Investments - Composition of Current and Past Due Mortgage Loans on Real Estate (Details) - USD ($) $ in Millions	Dec. 31, 2023	Dec. 31, 2022
Loans and Leases Receivable Disclosure [Line Items]
Allowance for credit losses	$ (114)	$ (98)
Unamortized premium (discount)	36	27
Mark-to-market gains (losses)	(37)	(27)
Total carrying value	18,873	18,211
Current
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	18,830	18,228
30 to 59 days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	89	42
60 to 89 days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	9	6
90 or more days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	60	33
Commercial
Loans and Leases Receivable Disclosure [Line Items]
Allowance for credit losses	(86)	(83)
Unamortized premium (discount)	(7)	(9)
Mark-to-market gains (losses)	(36)	(27)
Total carrying value	17,097	16,813
Commercial \| Current
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	17,165	16,913
Commercial \| 30 to 59 days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	61	19
Commercial \| 60 to 89 days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	0	0
Commercial \| 90 or more days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	0	0
Residential
Loans and Leases Receivable Disclosure [Line Items]
Allowance for credit losses	(28)	(15)
Unamortized premium (discount)	43	36
Mark-to-market gains (losses)	(1)	0
Total carrying value	1,776	1,398
Residential \| Current
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	1,665	1,315
Residential \| 30 to 59 days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	28	23
Residential \| 60 to 89 days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	9	6
Residential \| 90 or more days past due
Loans and Leases Receivable Disclosure [Line Items]
Mortgage loans on real estate, gross	$ 60	$ 33

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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