Fair Value Measurements - Changes in Level 3 Recurring Fair Value Measurements, Liabilities (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023	Jun. 30, 2024	Dec. 31, 2023	Jun. 30, 2023	Dec. 31, 2022
Derivative liabilities, net:
Fair Value Beginning of Year	$ 100	$ (925)	$ 100	$ (925)	$ (94)	$ (479)	$ (908)	$ (512)
Net Realized and Unrealized (Gains) Losses Included in Income	158	(60)	197	23
Other Comprehensive Income (Loss)	0	0	0	0
Purchases, Sales, Issuances and Settlements, Net	(1)	43	345	(436)
Gross Transfers In	0	0	0	0
Gross Transfers Out	0	0	0	0
Other	37	0	37	0
Fair Value End of Period	100	(925)	100	(925)
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	(151)	141	(99)	126
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	$ 0	$ 0	$ 0	$ 0
Fair Value, Liability, Recurring Basis, Unobservable Input Reconciliation, Gain (Loss), Statement of Income or Comprehensive Income [Extensible Enumeration]	Adjusted Revenues	Adjusted Revenues	Adjusted Revenues	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 income (loss)	Other comprehensive income (loss)	Other comprehensive income (loss)	Other comprehensive income (loss)
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]	Realized Investment Gains (Losses)	Realized Investment Gains (Losses)	Realized Investment Gains (Losses)	Realized Investment Gains (Losses)
Derivative liabilities, net
Derivative liabilities, net:
Fair Value Beginning of Year	$ (39)	$ (737)	$ (453)	$ (583)
Net Realized and Unrealized (Gains) Losses Included in Income	1	3	41	18
Other Comprehensive Income (Loss)	0	0	0	0
Purchases, Sales, Issuances and Settlements, Net	2	72	376	(97)
Gross Transfers In	0	0	0	0
Gross Transfers Out	0	0	0	0
Other	37	0	37	0
Fair Value End of Period	1	(662)	1	(662)
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	2	63	7	96
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	0	0	0	0
Net Realized and Unrealized (Gains) Losses Included in Income	1	3	41	18
Interest rate contracts
Derivative liabilities, net:
Fair Value Beginning of Year	(3)	(339)	(406)	(311)
Net Realized and Unrealized (Gains) Losses Included in Income	0	(174)	61	(90)
Other Comprehensive Income (Loss)	0	0	0	0
Purchases, Sales, Issuances and Settlements, Net	3	(20)	345	(132)
Gross Transfers In	0	0	0	0
Gross Transfers Out	0	0	0	0
Other	0	0	0	0
Fair Value End of Period	0	(533)	0	(533)
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	0	128	(3)	146
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	0	0	0	0
Foreign exchange contracts
Derivative liabilities, net:
Fair Value Beginning of Year		2	2	0
Net Realized and Unrealized (Gains) Losses Included in Income		(1)	(2)	1
Other Comprehensive Income (Loss)		0	0	0
Purchases, Sales, Issuances and Settlements, Net		1	0	1
Gross Transfers In		0	0	0
Gross Transfers Out		0	0	0
Other		0	0	0
Fair Value End of Period	0	2	0	2
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period		0	0	(2)
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period		0	0	0
Equity contracts
Derivative liabilities, net:
Fair Value Beginning of Year	(35)	(399)	(48)	(271)
Net Realized and Unrealized (Gains) Losses Included in Income	0	178	(18)	109
Other Comprehensive Income (Loss)	0	0	0	0
Purchases, Sales, Issuances and Settlements, Net	(1)	91	30	32
Gross Transfers In	0	0	0	0
Gross Transfers Out	0	0	0	0
Other	36	0	36	0
Fair Value End of Period	0	(130)	0	(130)
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	2	(65)	10	(49)
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	0	0	0	0
Credit contracts
Derivative liabilities, net:
Fair Value Beginning of Year	0	0	0	0
Net Realized and Unrealized (Gains) Losses Included in Income	1	1	1	0
Other Comprehensive Income (Loss)	0	0	0	0
Purchases, Sales, Issuances and Settlements, Net	0	(1)	0	0
Gross Transfers In	0	0	0	0
Gross Transfers Out	0	0	0	0
Other	0	0	0	0
Fair Value End of Period	1	0	1	0
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	(1)	(1)	(1)	(1)
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	0	0	0	0
Other contracts
Derivative liabilities, net:
Fair Value Beginning of Year	(1)	(1)	(1)	(1)
Net Realized and Unrealized (Gains) Losses Included in Income	0	(1)	(1)	(2)
Other Comprehensive Income (Loss)	0	0	0	0
Purchases, Sales, Issuances and Settlements, Net	0	1	1	2
Gross Transfers In	0	0	0	0
Gross Transfers Out	0	0	0	0
Other	1	0	1	0
Fair Value End of Period	0	(1)	0	(1)
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	1	1	1	2
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	0	0	0	0
Fortitude Re funds withheld payable
Derivative liabilities, net:
Fair Value Beginning of Year	0	(355)	0	(355)	(154)	(148)	(269)	(41)
Net Realized and Unrealized (Gains) Losses Included in Income	157	(57)	158	25
Other Comprehensive Income (Loss)	0	0	0	0
Purchases, Sales, Issuances and Settlements, Net	(3)	(29)	(10)	(339)
Gross Transfers In	0	0	0	0
Gross Transfers Out	0	0	0	0
Other	0	0	0	0
Fair Value End of Period	0	(355)	0	(355)
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	(153)	78	(106)	30
Changes in Unrealized Gains (Losses) Included in Other Comprehensive Income (Loss) for Recurring Level 3 Instruments Held at End of Period	0	0	0	0
Other Liabilities
Derivative liabilities, net:
Fair Value Beginning of Year	99	92	99	92	$ 99	$ 122	$ 98	$ 112
Net Realized and Unrealized (Gains) Losses Included in Income	0	(6)	(2)	(20)
Other Comprehensive Income (Loss)	0	0	0	0
Purchases, Sales, Issuances and Settlements, Net	0	0	(21)	0
Gross Transfers In	0	0	0	0
Gross Transfers Out	0	0	0	0
Other	0	0	0	0
Fair Value End of Period	99	92	99	92
Changes in Unrealized Gains (Losses) Included in Income on Instruments Held at End of Period	0	0	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	$ 0	$ 0