Fair Value Measurements - Net realized and unrealized gains and losses included in income related to Level 3 assets and liabilities (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2024	Mar. 31, 2023
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	$ 83	$ 31
Net realized gains (losses), liabilities	(115)	(1,292)
Policyholder contract deposits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	(452)	(381)
Policyholder contract deposits \| Policy Fees
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	0	0
Policyholder contract deposits \| Net Investment Income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	0	0
Policyholder contract deposits \| Net Realized and Unrealized Gains (Losses)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	(452)	(381)
Policyholder contract deposits \| Change in the fair value of market risk benefits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	0	0
Derivative liabilities, net
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	315	114
Derivative liabilities, net \| Policy Fees
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	15	16
Derivative liabilities, net \| Net Investment Income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	0	0
Derivative liabilities, net \| Net Realized and Unrealized Gains (Losses)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	363	197
Derivative liabilities, net \| Change in the fair value of market risk benefits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	(63)	(99)
Fortitude Re funds withheld payable
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	22	(1,025)
Fortitude Re funds withheld payable \| Policy Fees
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	0	0
Fortitude Re funds withheld payable \| Net Investment Income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	0	0
Fortitude Re funds withheld payable \| Net Realized and Unrealized Gains (Losses)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	22	(1,025)
Fortitude Re funds withheld payable \| Change in the fair value of market risk benefits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	0	0
Market Risk Benefit Liabilities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	1,071	(87)
Market Risk Benefit Liabilities \| Policy Fees
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	0	0
Market Risk Benefit Liabilities \| Net Investment Income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	0	0
Market Risk Benefit Liabilities \| Net Realized and Unrealized Gains (Losses)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	2	0
Market Risk Benefit Liabilities \| Change in the fair value of market risk benefits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), liabilities	1,069	(87)
Bonds available-for-sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	134	37
Bonds available-for-sale \| Policy Fees
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	0	0
Bonds available-for-sale \| Net Investment Income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	159	32
Bonds available-for-sale \| Net Realized and Unrealized Gains (Losses)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	(25)	5
Bonds available-for-sale \| Change in the fair value of market risk benefits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	0	0
Other bond securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	26	38
Other bond securities \| Policy Fees
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	0	0
Other bond securities \| Net Investment Income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	26	38
Other bond securities \| Net Realized and Unrealized Gains (Losses)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	0	0
Other bond securities \| Change in the fair value of market risk benefits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	0	0
Equity securities
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	3	0
Equity securities \| Policy Fees
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	0	0
Equity securities \| Net Investment Income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	3	0
Equity securities \| Net Realized and Unrealized Gains (Losses)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	0	0
Equity securities \| Change in the fair value of market risk benefits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	0	0
Other invested assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	(80)	(44)
Other invested assets \| Policy Fees
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	0	0
Other invested assets \| Net Investment Income
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	(78)	(43)
Other invested assets \| Net Realized and Unrealized Gains (Losses)
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	(2)	(1)
Other invested assets \| Change in the fair value of market risk benefits
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Net realized gains (losses), assets	$ 0	$ 0

Fair Value Measurements - Net realized and unrealized gains and losses included in income related to Level 3 assets and liabilities (Details) - USD ($)
$ in Millions