Fair Value Measurements - Assets and liabilities measured at fair value on a recurring basis (Details) - USD ($)		Jun. 30, 2022	Dec. 31, 2021
Assets:
Bonds available for sale	[1]	$ 232,735,000,000	$ 277,202,000,000
Other bond securities	[1]	6,898,000,000	6,278,000,000
Equity securities	[1]	629,000,000	739,000,000
Derivative assets		7,137,000,000	5,761,000,000
Counterparty netting		(4,354,000,000)	(2,779,000,000)
Cash Collateral		(2,426,000,000)	(2,139,000,000)
Total derivative assets		357,000,000	843,000,000
Short-term investments	[1]	9,446,000,000	13,357,000,000
Separate account assets		86,735,000,000	109,111,000,000
Liabilities:
Policyholder contract deposits		156,557,000,000	156,686,000,000
Derivative liabilities		7,052,000,000	4,454,000,000
Counterparty netting		(4,354,000,000)	(2,779,000,000)
Cash Collateral		(2,418,000,000)	(1,089,000,000)
Total derivative liabilities		280,000,000	586,000,000
Fortitude Re funds withheld payable		32,970,000,000	40,771,000,000
U.S. government and government sponsored entities
Assets:
Bonds available for sale		8,146,000,000	8,194,000,000
Obligations of states, municipalities and political subdivisions
Assets:
Bonds available for sale		12,600,000,000	14,527,000,000
Non-U.S. governments
Assets:
Bonds available for sale		13,674,000,000	16,330,000,000
Corporate debt
Assets:
Bonds available for sale		142,741,000,000	175,608,000,000
RMBS
Assets:
Bonds available for sale		20,173,000,000	27,287,000,000
CMBS
Assets:
Bonds available for sale		14,887,000,000	15,809,000,000
CDO/ABS
Assets:
Bonds available for sale		20,514,000,000	19,447,000,000
Level 3 | Obligations of states, municipalities and political subdivisions
Assets:
Bonds available for sale		913,000,000	1,400,000,000
Level 3 | Corporate debt
Assets:
Bonds available for sale		2,346,000,000	1,561,000,000
Level 3 | RMBS
Assets:
Bonds available for sale		5,843,000,000	9,916,000,000
Level 3 | CMBS
Assets:
Bonds available for sale		587,000,000	580,000,000
Fair Value Measured at Net Asset Value Per Share
Liabilities:
Fair Value Using NAV Per Share (or its equivalent)		9,600,000,000	8,400,000,000
Recurring Basis
Assets:
Counterparty netting		(4,354,000,000)	(2,779,000,000)
Cash Collateral		(2,426,000,000)	(2,139,000,000)
Counterparty netting and cash collateral		(6,780,000,000)	(4,918,000,000)
Total derivative assets		357,000,000	843,000,000
Short-term investments		3,431,000,000	4,426,000,000
Liabilities:
Policyholder contract deposits		6,997,000,000	9,736,000,000
Counterparty netting		(4,354,000,000)	(2,779,000,000)
Cash Collateral		(2,418,000,000)	(1,089,000,000)
Counterparty netting and cash collateral		(6,772,000,000)	(3,868,000,000)
Total derivative liabilities		280,000,000	586,000,000
Fortitude Re funds withheld payable		(638,000,000)
Fortitude Re funds withheld payable			5,922,000,000
Other liabilities		280,000,000	586,000,000
Long-term debt		1,664,000,000	1,871,000,000
Recurring Basis | Levels 1, 2 and 3
Assets:
Bonds available for sale		232,735,000,000	277,202,000,000
Other bond securities		6,898,000,000	6,278,000,000
Equity securities		629,000,000	739,000,000
Other invested assets		2,139,000,000	2,086,000,000
Short-term investments		3,431,000,000	4,426,000,000
Other assets		107,000,000	114,000,000
Separate account assets		86,735,000,000	109,111,000,000
Total		333,031,000,000	400,799,000,000
Liabilities:
Policyholder contract deposits		6,997,000,000	9,736,000,000
Fortitude Re funds withheld payable		(638,000,000)
Fortitude Re funds withheld payable			5,922,000,000
Long-term debt		1,664,000,000	1,871,000,000
Total		8,303,000,000	18,115,000,000
Recurring Basis | Levels 1, 2 and 3 | Interest rate contracts
Assets:
Derivative assets		4,611,000,000	3,873,000,000
Liabilities:
Derivative liabilities		6,307,000,000	3,633,000,000
Recurring Basis | Levels 1, 2 and 3 | Foreign exchange contracts
Assets:
Derivative assets		2,113,000,000	1,189,000,000
Liabilities:
Derivative liabilities		648,000,000	721,000,000
Recurring Basis | Levels 1, 2 and 3 | Equity contracts
Assets:
Derivative assets		387,000,000	681,000,000
Liabilities:
Derivative liabilities		53,000,000	53,000,000
Recurring Basis | Levels 1, 2 and 3 | Commodity contracts
Assets:
Derivative assets		9,000,000	4,000,000
Recurring Basis | Levels 1, 2 and 3 | Credit contracts
Assets:
Derivative assets		1,000,000	1,000,000
Liabilities:
Derivative liabilities		44,000,000	47,000,000
Recurring Basis | Levels 1, 2 and 3 | Other contracts
Assets:
Derivative assets		16,000,000	13,000,000
Recurring Basis | Levels 1, 2 and 3 | U.S. government and government sponsored entities
Assets:
Bonds available for sale		8,146,000,000	8,194,000,000
Other bond securities		1,620,000,000	1,750,000,000
Recurring Basis | Levels 1, 2 and 3 | Obligations of states, municipalities and political subdivisions
Assets:
Bonds available for sale		12,600,000,000	14,527,000,000
Other bond securities		99,000,000	97,000,000
Recurring Basis | Levels 1, 2 and 3 | Non-U.S. governments
Assets:
Bonds available for sale		13,674,000,000	16,330,000,000
Other bond securities		76,000,000	76,000,000
Recurring Basis | Levels 1, 2 and 3 | Corporate debt
Assets:
Bonds available for sale		142,741,000,000	175,608,000,000
Other bond securities		1,661,000,000	1,050,000,000
Recurring Basis | Levels 1, 2 and 3 | RMBS
Assets:
Bonds available for sale		20,173,000,000	27,287,000,000
Other bond securities		294,000,000	411,000,000
Recurring Basis | Levels 1, 2 and 3 | CMBS
Assets:
Bonds available for sale		14,887,000,000	15,809,000,000
Other bond securities		321,000,000	315,000,000
Recurring Basis | Levels 1, 2 and 3 | CDO/ABS
Assets:
Bonds available for sale		20,514,000,000	19,447,000,000
Other bond securities		2,827,000,000	2,579,000,000
Recurring Basis | Level 1
Assets:
Bonds available for sale		149,000,000	2,562,000,000
Other bond securities		0	0
Equity securities		583,000,000	669,000,000
Other invested assets		0	0
Derivative assets		21,000,000	7,000,000
Short-term investments		1,874,000,000	2,584,000,000
Other assets		0	0
Separate account assets		82,990,000,000	105,221,000,000
Total		85,617,000,000	111,043,000,000
Liabilities:
Policyholder contract deposits		0	0
Derivative liabilities		14,000,000	2,000,000
Fortitude Re funds withheld payable		0
Fortitude Re funds withheld payable			0
Long-term debt		0	0
Total		14,000,000	2,000,000
Recurring Basis | Level 1 | Interest rate contracts
Assets:
Derivative assets		0	0
Liabilities:
Derivative liabilities		10,000,000	1,000,000
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		21,000,000	7,000,000
Liabilities:
Derivative liabilities		4,000,000	1,000,000
Recurring Basis | Level 1 | Commodity contracts
Assets:
Derivative assets		0	0
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
Recurring Basis | Level 1 | U.S. government and government sponsored entities
Assets:
Bonds available for sale		0	2,553,000,000
Other bond securities		0	0
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		149,000,000	9,000,000
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 | CDO/ABS
Assets:
Bonds available for sale		0	0
Other bond securities		0	0
Recurring Basis | Level 2
Assets:
Bonds available for sale		208,218,000,000	247,778,000,000
Other bond securities		3,771,000,000	3,581,000,000
Equity securities		34,000,000	64,000,000
Other invested assets		131,000,000	138,000,000
Derivative assets		6,796,000,000	5,289,000,000
Short-term investments		1,557,000,000	1,842,000,000
Other assets		0	0
Separate account assets		3,745,000,000	3,890,000,000
Total		224,252,000,000	262,582,000,000
Liabilities:
Policyholder contract deposits		40,000,000	54,000,000
Derivative liabilities		6,993,000,000	4,415,000,000
Fortitude Re funds withheld payable		0
Fortitude Re funds withheld payable			0
Long-term debt		1,664,000,000	1,871,000,000
Total		8,697,000,000	6,340,000,000
Recurring Basis | Level 2 | Interest rate contracts
Assets:
Derivative assets		4,460,000,000	3,873,000,000
Liabilities:
Derivative liabilities		6,289,000,000	3,632,000,000
Recurring Basis | Level 2 | Foreign exchange contracts
Assets:
Derivative assets		2,113,000,000	1,188,000,000
Liabilities:
Derivative liabilities		647,000,000	721,000,000
Recurring Basis | Level 2 | Equity contracts
Assets:
Derivative assets		214,000,000	224,000,000
Liabilities:
Derivative liabilities		46,000,000	46,000,000
Recurring Basis | Level 2 | Commodity contracts
Assets:
Derivative assets		9,000,000	4,000,000
Recurring Basis | Level 2 | Credit contracts
Assets:
Derivative assets		0	0
Liabilities:
Derivative liabilities		11,000,000	16,000,000
Recurring Basis | Level 2 | Other contracts
Assets:
Derivative assets		0	0
Recurring Basis | Level 2 | U.S. government and government sponsored entities
Assets:
Bonds available for sale		8,146,000,000	5,641,000,000
Other bond securities		1,620,000,000	1,750,000,000
Recurring Basis | Level 2 | Obligations of states, municipalities and political subdivisions
Assets:
Bonds available for sale		11,643,000,000	13,096,000,000
Other bond securities		99,000,000	97,000,000
Recurring Basis | Level 2 | Non-U.S. governments
Assets:
Bonds available for sale		13,516,000,000	16,314,000,000
Other bond securities		76,000,000	76,000,000
Recurring Basis | Level 2 | Corporate debt
Assets:
Bonds available for sale		140,258,000,000	172,967,000,000
Other bond securities		1,200,000,000	916,000,000
Recurring Basis | Level 2 | RMBS
Assets:
Bonds available for sale		11,821,000,000	16,909,000,000
Other bond securities		102,000,000	215,000,000
Recurring Basis | Level 2 | CMBS
Assets:
Bonds available for sale		14,016,000,000	14,619,000,000
Other bond securities		289,000,000	280,000,000
Recurring Basis | Level 2 | CDO/ABS
Assets:
Bonds available for sale		8,818,000,000	8,232,000,000
Other bond securities		385,000,000	247,000,000
Recurring Basis | Level 3
Assets:
Bonds available for sale		24,368,000,000	26,862,000,000
Other bond securities		3,127,000,000	2,697,000,000
Equity securities		12,000,000	6,000,000
Other invested assets		2,008,000,000	1,948,000,000
Derivative assets		320,000,000	465,000,000
Short-term investments		0	0
Other assets		107,000,000	114,000,000
Separate account assets		0	0
Total		29,942,000,000	32,092,000,000
Liabilities:
Policyholder contract deposits		6,957,000,000	9,682,000,000
Derivative liabilities		45,000,000	37,000,000
Fortitude Re funds withheld payable		(638,000,000)
Fortitude Re funds withheld payable			5,922,000,000
Long-term debt		0	0
Total		6,364,000,000	15,641,000,000
Recurring Basis | Level 3 | Interest rate contracts
Assets:
Derivative assets		151,000,000	0
Liabilities:
Derivative liabilities		8,000,000	0
Recurring Basis | Level 3 | Foreign exchange contracts
Assets:
Derivative assets		0	1,000,000
Liabilities:
Derivative liabilities		1,000,000	0
Recurring Basis | Level 3 | Equity contracts
Assets:
Derivative assets		152,000,000	450,000,000
Liabilities:
Derivative liabilities		3,000,000	6,000,000
Recurring Basis | Level 3 | Commodity contracts
Assets:
Derivative assets		0	0
Recurring Basis | Level 3 | Credit contracts
Assets:
Derivative assets		1,000,000	1,000,000
Liabilities:
Derivative liabilities		33,000,000	31,000,000
Recurring Basis | Level 3 | Other contracts
Assets:
Derivative assets		16,000,000	13,000,000
Recurring Basis | Level 3 | U.S. government and government sponsored entities
Assets:
Bonds available for sale		0	0
Other bond securities		0	0
Recurring Basis | Level 3 | Obligations of states, municipalities and political subdivisions
Assets:
Bonds available for sale		957,000,000	1,431,000,000
Other bond securities		0	0
Recurring Basis | Level 3 | Non-U.S. governments
Assets:
Bonds available for sale		9,000,000	7,000,000
Other bond securities		0	0
Recurring Basis | Level 3 | Corporate debt
Assets:
Bonds available for sale		2,483,000,000	2,641,000,000
Other bond securities		461,000,000	134,000,000
Recurring Basis | Level 3 | RMBS
Assets:
Bonds available for sale		8,352,000,000	10,378,000,000
Other bond securities		192,000,000	196,000,000
Recurring Basis | Level 3 | CMBS
Assets:
Bonds available for sale		871,000,000	1,190,000,000
Other bond securities		32,000,000	35,000,000
Recurring Basis | Level 3 | CDO/ABS
Assets:
Bonds available for sale		11,696,000,000	11,215,000,000
Other bond securities		$ 2,442,000,000	$ 2,332,000,000

[1] See Note 8 for details of balances associated with variable interest entities.