Fair Value Measurements - Financial Instruments Not Carried at Fair Value (Details) - USD ($) $ in Millions	Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023	Dec. 31, 2022
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing Receivable, after Allowance for Credit Loss	$ 6,197	$ 6,087
Other policyholder funds and benefits payable	633	638	$ 647
Commercial Loan [Member]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing Receivable, Allowance for Credit Loss	48	51	$ 36	$ 36
Financing Receivable, after Allowance for Credit Loss	6,197	6,087
Significant Unobservable Inputs (Level 3) | Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing Receivable, after Allowance for Credit Loss	6,197	6,087
Other policyholder funds and benefits payable	633	638
Significant Unobservable Inputs (Level 3) | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Financing Receivable, after Allowance for Credit Loss	5,618	5,584
Other policyholder funds and benefits payable	633	639
Significant Observable Inputs (Level 2) | Carrying Amount
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior Notes	3,864	3,863
Junior Subordinated Debentures	499	499
Significant Observable Inputs (Level 2) | Fair Value
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Senior Notes	3,491	3,533
Junior Subordinated Debentures	$ 445	$ 429