Fair Value Measurements - Changes in Level 3 Recurring Fair Value Measurements, Liabilities (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023	Dec. 31, 2022
Liabilities:
Fair Value Beginning of Period	$ 5,839	$ 3,441	$ 5,607	$ 2,648
MRBs and Net Realized and Unrealized (Gains) Losses Included in Income	304	1,531
Other Comprehensive Income (Loss)	0	0
Purchases, Sales, Issuances and Settlements, Net	(72)	(738)
Gross Transfers In		0
Gross Transfers Out	0	0
Other	0	0
Fair Value End of Period	5,839	3,441
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	602	(1,110)
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	$ 0	$ 136
Derivative liabilities, net:
Fair Value, Liability, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Adjusted Revenues
Fair Value, Liability, Recurring Basis, Unobservable Input Reconciliation, Liability, Gain (Loss), Statement of Other Comprehensive Income or Comprehensive Income [Extensible Enumeration]	Other comprehensive (loss) income	Other comprehensive (loss) income
Market risk benefit liabilities, at fair value	$ 5,167		5,705
Recurring Basis
Derivative liabilities, net:
Market risk benefit liabilities, at fair value	5,167		5,705
Level 3 | Recurring Basis
Derivative liabilities, net:
Market risk benefit liabilities, at fair value	$ 5,167	$ 5,100	5,705
Net realized gains/(losses)
Derivative liabilities, net:
Fair Value, Liability, Recurring Basis, Still Held, Unrealized Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Total net realized losses	Total net realized losses
Policyholder contract deposits
Liabilities:
Fair Value Beginning of Period	$ 8,550	$ 6,064	7,942	5,367
MRBs and Net Realized and Unrealized (Gains) Losses Included in Income	452	381
Other Comprehensive Income (Loss)	0	0
Purchases, Sales, Issuances and Settlements, Net	156	316
Gross Transfers In	0	0
Gross Transfers Out	0	0
Other	0	0
Fair Value End of Period	8,550	6,064
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	(3)	(368)
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	0	0
Derivative liabilities, net
Liabilities:
MRBs and Net Realized and Unrealized (Gains) Losses Included in Income	(105)	(15)
Purchases, Sales, Issuances and Settlements, Net	(103)	(261)
Derivative liabilities, net:
Fair Value Beginning of Period	(1,231)	(596)
MRBs and Net Realized and Unrealized (Gains) Losses Included in Income	(105)	(15)
Other Comprehensive Income (Loss)	0	0
Purchases, Sales, Issuances and Settlements, Net	(103)	(261)
Gross Transfers In	0	0
Gross Transfers Out	0	0
Other	0	0
Fair Value End of Period	(1,439)	(872)
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	396	17
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	0	136
Interest rate contracts
Derivative liabilities, net:
Fair Value Beginning of Period	(460)	(311)
MRBs and Net Realized and Unrealized (Gains) Losses Included in Income	103	57
Other Comprehensive Income (Loss)	0	0
Purchases, Sales, Issuances and Settlements, Net	(53)	(102)
Gross Transfers In	0	0
Gross Transfers Out	0	0
Other	0	0
Fair Value End of Period	(410)	(356)
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	193	(50)
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	0	0
Foreign exchange contracts
Derivative liabilities, net:
Fair Value Beginning of Period	2
MRBs and Net Realized and Unrealized (Gains) Losses Included in Income	0
Other Comprehensive Income (Loss)	0
Purchases, Sales, Issuances and Settlements, Net	0
Gross Transfers In	0
Gross Transfers Out	0
Other	0
Fair Value End of Period	2
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	0
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	0
Equity contracts
Derivative liabilities, net:
Fair Value Beginning of Period	(762)	(271)
MRBs and Net Realized and Unrealized (Gains) Losses Included in Income	(192)	(56)
Other Comprehensive Income (Loss)	0	0
Purchases, Sales, Issuances and Settlements, Net	(65)	(175)
Gross Transfers In	0	0
Gross Transfers Out	0	0
Other	0	0
Fair Value End of Period	(1,019)	(502)
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	187	51
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	0	136
Other contracts
Derivative liabilities, net:
Fair Value Beginning of Period	(11)	(14)
MRBs and Net Realized and Unrealized (Gains) Losses Included in Income	(16)	(16)
Other Comprehensive Income (Loss)	0	0
Purchases, Sales, Issuances and Settlements, Net	15	16
Gross Transfers In	0	0
Gross Transfers Out	0	0
Other	0	0
Fair Value End of Period	(12)	(14)
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	16	16
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	0	0
Fortitude Re funds withheld payable
Liabilities:
Fair Value Beginning of Period	(1,364)	(1,863)	(1,226)	(2,235)
MRBs and Net Realized and Unrealized (Gains) Losses Included in Income	(13)	1,165
Other Comprehensive Income (Loss)	0	0
Purchases, Sales, Issuances and Settlements, Net	(125)	(793)
Gross Transfers In	0	0
Gross Transfers Out	0	0
Other	0	0
Fair Value End of Period	(1,364)	(1,863)
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	209	(759)
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	0	0
Other Liabilities
Liabilities:
Fair Value Beginning of Period	92	112	$ 122	$ 112
MRBs and Net Realized and Unrealized (Gains) Losses Included in Income	(30)	0
Other Comprehensive Income (Loss)	0	0
Purchases, Sales, Issuances and Settlements, Net	0	0
Gross Transfers In	0	0
Gross Transfers Out	0	0
Other	0	0
Fair Value End of Period	92	112
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	0	0
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	$ 0	$ 0