Fair Value Measurements - Assets and Liabilities Measured at Fair Value on a Recurring Basis (Details) - USD ($)		Mar. 31, 2024	Dec. 31, 2023	Mar. 31, 2023
Assets:
Bonds available for sale	[1]	$ 232,487,000,000	$ 231,733,000,000
Other bond securities	[1]	5,403,000,000	5,241,000,000
Equity securities	[1]	797,000,000	728,000,000
Derivative assets		7,722,000,000	6,595,000,000
Counterparty netting		(4,545,000,000)	(3,864,000,000)
Cash Collateral		$ (2,601,000,000)	$ (2,220,000,000)
Derivative Asset, Statement of Financial Position [Extensible Enumeration]		Other assets	Other assets
Total derivative assets		$ 576,000,000	$ 511,000,000
Short-term investments	[1]	15,077,000,000	17,200,000,000
Market risk benefit assets		1,172,000,000	912,000,000
Separate account assets		95,173,000,000	91,005,000,000
Liabilities:
Policyholder contract deposits		163,698,000,000	161,979,000,000
Market risk benefit liabilities, at fair value		5,167,000,000	5,705,000,000
Derivative liabilities		5,272,000,000	5,309,000,000
Counterparty netting		(4,545,000,000)	(3,864,000,000)
Cash Collateral		$ (326,000,000)	$ (1,050,000,000)
Derivative Liability, Statement of Financial Position [Extensible Enumeration]		Other liabilities	Other liabilities
Total derivative liabilities		$ 401,000,000	$ 395,000,000
Fortitude Re funds withheld payable		(28,789,000,000)	(29,484,000,000)
Fair Value Using NAV Per Share (or its equivalent)		11,195,000,000	11,320,000,000
U.S. government and government sponsored entities
Assets:
Bonds available for sale		5,789,000,000	5,616,000,000
Obligations of states, municipalities and political subdivisions
Assets:
Bonds available for sale		10,093,000,000	10,663,000,000
Non-U.S. governments
Assets:
Bonds available for sale		11,968,000,000	12,453,000,000
Corporate debt
Assets:
Bonds available for sale		135,818,000,000	138,432,000,000
RMBS
Assets:
Bonds available for sale		21,421,000,000	20,444,000,000
CMBS
Assets:
Bonds available for sale		14,488,000,000	14,128,000,000
CLO/ABS
Assets:
Bonds available for sale		32,910,000,000	29,997,000,000
Level 3
Liabilities:
Policyholder contract deposits		1,700,000,000	1,500,000,000
Level 3 | Obligations of states, municipalities and political subdivisions
Assets:
Bonds available for sale		809,000,000	824,000,000
Level 3 | Corporate debt
Assets:
Bonds available for sale		1,945,000,000	1,803,000,000
Level 3 | RMBS
Assets:
Bonds available for sale		4,672,000,000	4,656,000,000
Level 3 | CMBS
Assets:
Bonds available for sale		547,000,000	587,000,000
Fair Value Measured at Net Asset Value Per Share
Liabilities:
Fair Value Using NAV Per Share (or its equivalent)		9,500,000,000	9,500,000,000
Recurring Basis
Assets:
Counterparty netting		(4,545,000,000)	(3,864,000,000)
Cash Collateral		(2,601,000,000)	(2,220,000,000)
Counterparty netting and cash collateral		(7,146,000,000)	(6,084,000,000)
Total derivative assets		576,000,000	511,000,000
Short-term investments		8,487,000,000	10,772,000,000
Market risk benefit assets		1,172,000,000	912,000,000
Liabilities:
Policyholder contract deposits		8,613,000,000	7,997,000,000
Market risk benefit liabilities, at fair value		5,167,000,000	5,705,000,000
Counterparty netting		(4,545,000,000)	(3,864,000,000)
Cash Collateral		(326,000,000)	(1,050,000,000)
Counterparty netting and cash collateral		(4,871,000,000)	(4,914,000,000)
Total derivative liabilities		401,000,000	395,000,000
Fortitude Re funds withheld payable		(1,364,000,000)	(1,226,000,000)
Other liabilities		493,000,000	624,000,000
Long-term debt		68,000,000	53,000,000
Recurring Basis | Levels 1, 2 and 3
Assets:
Bonds available for sale		232,487,000,000	231,733,000,000
Other bond securities		5,403,000,000	5,241,000,000
Equity securities		797,000,000	728,000,000
Other invested assets		1,988,000,000	2,225,000,000
Short-term investments		8,487,000,000	10,772,000,000
Other assets		129,000,000	243,000,000
Separate account assets		95,173,000,000	91,005,000,000
Total		346,212,000,000	343,370,000,000
Liabilities:
Policyholder contract deposits		8,613,000,000	7,997,000,000
Fortitude Re funds withheld payable		(1,364,000,000)
Fortitude Re funds withheld payable			(1,226,000,000)
Other liabilities		92,000,000	229,000,000
Long-term debt		68,000,000	53,000,000
Total		12,977,000,000	13,153,000,000
Recurring Basis | Levels 1, 2 and 3 | Discontinued Operations, Excluding Held-for-Sale
Assets:
Total		176,000,000	182,000,000
Recurring Basis | Levels 1, 2 and 3 | Interest rate contracts
Assets:
Derivative assets		3,484,000,000	3,286,000,000
Liabilities:
Derivative liabilities		3,379,000,000	3,631,000,000
Recurring Basis | Levels 1, 2 and 3 | Foreign exchange contracts
Assets:
Derivative assets		1,236,000,000	1,236,000,000
Liabilities:
Derivative liabilities		627,000,000	894,000,000
Recurring Basis | Levels 1, 2 and 3 | Equity contracts
Assets:
Derivative assets		2,878,000,000	2,019,000,000
Liabilities:
Derivative liabilities		1,229,000,000	745,000,000
Recurring Basis | Levels 1, 2 and 3 | Credit contracts
Assets:
Derivative assets		111,000,000	41,000,000
Liabilities:
Derivative liabilities		36,000,000	37,000,000
Recurring Basis | Levels 1, 2 and 3 | Other contracts
Assets:
Derivative assets		13,000,000	13,000,000
Liabilities:
Derivative liabilities		1,000,000	2,000,000
Recurring Basis | Levels 1, 2 and 3 | U.S. government and government sponsored entities
Assets:
Bonds available for sale		5,789,000,000	5,616,000,000
Recurring Basis | Levels 1, 2 and 3 | Obligations of states, municipalities and political subdivisions
Assets:
Bonds available for sale		10,093,000,000	10,663,000,000
Other bond securities		90,000,000	91,000,000
Recurring Basis | Levels 1, 2 and 3 | Non-U.S. governments
Assets:
Bonds available for sale		11,968,000,000	12,453,000,000
Other bond securities		39,000,000	37,000,000
Recurring Basis | Levels 1, 2 and 3 | Corporate debt
Assets:
Bonds available for sale		135,818,000,000	138,432,000,000
Other bond securities		2,997,000,000	2,908,000,000
Recurring Basis | Levels 1, 2 and 3 | RMBS
Assets:
Bonds available for sale		21,421,000,000	20,444,000,000
Other bond securities		273,000,000	263,000,000
Recurring Basis | Levels 1, 2 and 3 | CMBS
Assets:
Bonds available for sale		14,488,000,000	14,128,000,000
Other bond securities		283,000,000	261,000,000
Recurring Basis | Levels 1, 2 and 3 | CLO/ABS
Assets:
Bonds available for sale		32,910,000,000	29,997,000,000
Other bond securities		1,721,000,000	1,681,000,000
Recurring Basis | Level 1
Assets:
Bonds available for sale		188,000,000	268,000,000
Other bond securities		0	0
Equity securities		727,000,000	632,000,000
Other invested assets		0	0
Derivative assets		0	7,000,000
Short-term investments		2,969,000,000	2,635,000,000
Market risk benefit assets		0	0
Other assets		0	0
Separate account assets		91,859,000,000	87,814,000,000
Total		95,743,000,000	91,356,000,000
Liabilities:
Policyholder contract deposits		0	0
Market risk benefit liabilities, at fair value		0	0
Derivative liabilities		0	2,000,000
Fortitude Re funds withheld payable		0
Fortitude Re funds withheld payable			0
Other liabilities		0	0
Long-term debt		0	0
Total		0	2,000,000
Recurring Basis | Level 1 | Interest rate contracts
Assets:
Derivative assets		0	0
Liabilities:
Derivative liabilities		0	0
Recurring Basis | Level 1 | Foreign exchange contracts
Assets:
Derivative assets		0	0
Liabilities:
Derivative liabilities		0	0
Recurring Basis | Level 1 | Equity contracts
Assets:
Derivative assets		0	7,000,000
Liabilities:
Derivative liabilities		0	2,000,000
Recurring Basis | Level 1 | Credit contracts
Assets:
Derivative assets		0	0
Liabilities:
Derivative liabilities		0	0
Recurring Basis | Level 1 | Other contracts
Assets:
Derivative assets		0	0
Liabilities:
Derivative liabilities		0	0
Recurring Basis | Level 1 | U.S. government and government sponsored entities
Assets:
Bonds available for sale		25,000,000	35,000,000
Recurring Basis | Level 1 | Obligations of states, municipalities and political subdivisions
Assets:
Bonds available for sale		0	0
Other bond securities		0	0
Recurring Basis | Level 1 | Non-U.S. governments
Assets:
Bonds available for sale		163,000,000	233,000,000
Other bond securities		0	0
Recurring Basis | Level 1 | Corporate debt
Assets:
Bonds available for sale		0	0
Other bond securities		0	0
Recurring Basis | Level 1 | RMBS
Assets:
Bonds available for sale		0	0
Other bond securities		0	0
Recurring Basis | Level 1 | CMBS
Assets:
Bonds available for sale		0	0
Other bond securities		0	0
Recurring Basis | Level 1 | CLO/ABS
Assets:
Bonds available for sale		0	0
Other bond securities		0	0
Recurring Basis | Level 2
Assets:
Bonds available for sale		202,753,000,000	204,621,000,000
Other bond securities		3,842,000,000	3,685,000,000
Equity securities		12,000,000	40,000,000
Other invested assets		134,000,000	155,000,000
Derivative assets		6,192,000,000	5,256,000,000
Short-term investments		5,518,000,000	8,137,000,000
Market risk benefit assets		0	0
Other assets		0	0
Separate account assets		3,314,000,000	3,191,000,000
Total		221,765,000,000	225,085,000,000
Liabilities:
Policyholder contract deposits		63,000,000	55,000,000
Market risk benefit liabilities, at fair value		0	0
Derivative liabilities		5,181,000,000	5,206,000,000
Fortitude Re funds withheld payable		0
Fortitude Re funds withheld payable			0
Other liabilities		0	107,000,000
Long-term debt		68,000,000	53,000,000
Total		5,312,000,000	5,421,000,000
Recurring Basis | Level 2 | Interest rate contracts
Assets:
Derivative assets		3,074,000,000	2,826,000,000
Liabilities:
Derivative liabilities		3,379,000,000	3,631,000,000
Recurring Basis | Level 2 | Foreign exchange contracts
Assets:
Derivative assets		1,235,000,000	1,235,000,000
Liabilities:
Derivative liabilities		624,000,000	891,000,000
Recurring Basis | Level 2 | Equity contracts
Assets:
Derivative assets		1,805,000,000	1,187,000,000
Liabilities:
Derivative liabilities		1,175,000,000	680,000,000
Recurring Basis | Level 2 | Credit contracts
Assets:
Derivative assets		78,000,000	8,000,000
Liabilities:
Derivative liabilities		3,000,000	4,000,000
Recurring Basis | Level 2 | Other contracts
Assets:
Derivative assets		0	0
Liabilities:
Derivative liabilities		0	0
Recurring Basis | Level 2 | U.S. government and government sponsored entities
Assets:
Bonds available for sale		5,764,000,000	5,581,000,000
Recurring Basis | Level 2 | Obligations of states, municipalities and political subdivisions
Assets:
Bonds available for sale		9,260,000,000	9,816,000,000
Other bond securities		89,000,000	90,000,000
Recurring Basis | Level 2 | Non-U.S. governments
Assets:
Bonds available for sale		11,798,000,000	12,213,000,000
Other bond securities		39,000,000	37,000,000
Recurring Basis | Level 2 | Corporate debt
Assets:
Bonds available for sale		133,861,000,000	136,753,000,000
Other bond securities		2,775,000,000	2,697,000,000
Recurring Basis | Level 2 | RMBS
Assets:
Bonds available for sale		13,308,000,000	12,804,000,000
Other bond securities		113,000,000	105,000,000
Recurring Basis | Level 2 | CMBS
Assets:
Bonds available for sale		13,898,000,000	13,495,000,000
Other bond securities		266,000,000	244,000,000
Recurring Basis | Level 2 | CLO/ABS
Assets:
Bonds available for sale		14,864,000,000	13,959,000,000
Other bond securities		560,000,000	512,000,000
Recurring Basis | Level 3
Assets:
Bonds available for sale		29,546,000,000	26,844,000,000
Other bond securities		1,561,000,000	1,556,000,000
Equity securities		58,000,000	56,000,000
Other invested assets		1,854,000,000	2,070,000,000
Derivative assets		1,530,000,000	1,332,000,000
Short-term investments		0	0
Market risk benefit assets		1,172,000,000	912,000,000	$ 830,000,000
Other assets		129,000,000	243,000,000
Separate account assets		0	0
Total		35,850,000,000	33,013,000,000
Liabilities:
Policyholder contract deposits		8,550,000,000	7,942,000,000
Market risk benefit liabilities, at fair value		5,167,000,000	5,705,000,000	$ 5,100,000,000
Derivative liabilities		91,000,000	101,000,000
Fortitude Re funds withheld payable		(1,364,000,000)
Fortitude Re funds withheld payable			(1,226,000,000)
Other liabilities		92,000,000	122,000,000
Long-term debt		0	0
Total		12,536,000,000	12,644,000,000
Recurring Basis | Level 3 | Interest rate contracts
Assets:
Derivative assets		410,000,000	460,000,000
Liabilities:
Derivative liabilities		0	0
Recurring Basis | Level 3 | Foreign exchange contracts
Assets:
Derivative assets		1,000,000	1,000,000
Liabilities:
Derivative liabilities		3,000,000	3,000,000
Recurring Basis | Level 3 | Equity contracts
Assets:
Derivative assets		1,073,000,000	825,000,000
Liabilities:
Derivative liabilities		54,000,000	63,000,000
Recurring Basis | Level 3 | Credit contracts
Assets:
Derivative assets		33,000,000	33,000,000
Liabilities:
Derivative liabilities		33,000,000	33,000,000
Recurring Basis | Level 3 | Other contracts
Assets:
Derivative assets		13,000,000	13,000,000
Liabilities:
Derivative liabilities		1,000,000	2,000,000
Recurring Basis | Level 3 | U.S. government and government sponsored entities
Assets:
Bonds available for sale		0	0
Recurring Basis | Level 3 | Obligations of states, municipalities and political subdivisions
Assets:
Bonds available for sale		833,000,000	847,000,000
Other bond securities		1,000,000	1,000,000
Recurring Basis | Level 3 | Non-U.S. governments
Assets:
Bonds available for sale		7,000,000	7,000,000
Other bond securities		0	0
Recurring Basis | Level 3 | Corporate debt
Assets:
Bonds available for sale		1,957,000,000	1,679,000,000
Other bond securities		222,000,000	211,000,000
Recurring Basis | Level 3 | RMBS
Assets:
Bonds available for sale		8,113,000,000	7,640,000,000
Other bond securities		160,000,000	158,000,000
Recurring Basis | Level 3 | CMBS
Assets:
Bonds available for sale		590,000,000	633,000,000
Other bond securities		17,000,000	17,000,000
Recurring Basis | Level 3 | CLO/ABS
Assets:
Bonds available for sale		18,046,000,000	16,038,000,000
Other bond securities		$ 1,161,000,000	$ 1,169,000,000

[1] See Note 10 for details of balances associated with variable interest entities.