Fair Value Measurements (Financial Instruments Measured At Fair Value on Recurring Basis) (Details) - USD ($) $ in Millions	Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2021
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	$ 106,571		$ 85,220
Equity securities	3,455		827
Short-term investments	4,551		4,960
Other investments	5,527		1,341
Securities lending collateral	1,299		1,523
Separate account assets	5,573		5,190		$ 5,560
Market risk benefits	771		800
Investment Funds Limited Partnerships Partially Owned Investment Companies Fair Value [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Other investments	14,078		12,355
Policy Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Other investments	702		390
U.S. Treasury / Agency
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	3,590		2,626
Debt Security, Government, Non-US [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	35,164		25,908
Corporate securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	42,830		36,955
Mortgage-backed securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	22,058		15,851
States, municipalities, and political subdivisions
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	2,929		3,880
Level 1 | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	2,911		2,100
Equity securities	3,368		737
Short-term investments	1,915		3,108
Other investments	589	[1]	552	[2]
Securities lending collateral	0		0
Investment derivative instruments, assets	54		82
Derivative Instruments in Hedges, Assets, at Fair Value	0		0
Other Derivative Instruments Fair Value			33
Separate account assets	5,482		5,101
Assets, Fair Value Disclosure	14,319	[1],[3]	11,713	[2]
Investment derivative instruments, liability	136		139
Derivative Instruments in Hedges, Liabilities, at Fair Value	0
Other derivative instruments, liability	37		0
Liabilities Related to Investment Contracts, Fair Value Disclosure	173		139
Level 1 | Fair Value, Recurring [Member] | Guaranteed Minimum Income Benefit
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Market risk benefits	0	[4]	0	[5]
Level 1 | U.S. Treasury / Agency | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	2,911		2,100
Level 1 | Debt Security, Government, Non-US [Member] | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	0		0
Level 1 | Corporate securities | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	0		0
Level 1 | Mortgage-backed securities | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	0		0
Level 1 | States, municipalities, and political subdivisions | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	0		0
Level 2 | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	100,339		80,096
Equity securities	0		0
Short-term investments	2,633		1,849
Other investments	4,236	[1]	399	[2]
Securities lending collateral	1,299		1,523
Investment derivative instruments, assets	0		0
Derivative Instruments in Hedges, Assets, at Fair Value	136		17
Other Derivative Instruments Fair Value			0
Separate account assets	91		89
Assets, Fair Value Disclosure	108,734	[1],[3]	83,973	[2]
Investment derivative instruments, liability	0		0
Derivative Instruments in Hedges, Liabilities, at Fair Value	128
Other derivative instruments, liability	5		53
Liabilities Related to Investment Contracts, Fair Value Disclosure	133		53
Level 2 | Fair Value, Recurring [Member] | Guaranteed Minimum Income Benefit
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Market risk benefits	0	[4]	0	[5]
Level 2 | U.S. Treasury / Agency | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	679		526
Level 2 | Debt Security, Government, Non-US [Member] | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	34,472		25,344
Level 2 | Corporate securities | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	40,208		34,506
Level 2 | Mortgage-backed securities | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	22,051		15,840
Level 2 | States, municipalities, and political subdivisions | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	2,929		3,880
Level 3 | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	3,321		3,024
Equity securities	87		90
Short-term investments	3		3
Other investments	0	[1]	0	[2]
Securities lending collateral	0		0
Investment derivative instruments, assets	0		0
Derivative Instruments in Hedges, Assets, at Fair Value	0		0
Other Derivative Instruments Fair Value			0
Separate account assets	0		0
Assets, Fair Value Disclosure	3,411	[1],[3]	3,117	[2]
Investment derivative instruments, liability	0		0
Derivative Instruments in Hedges, Liabilities, at Fair Value	0
Other derivative instruments, liability	0		0
Liabilities Related to Investment Contracts, Fair Value Disclosure	771		800
Level 3 | Fair Value, Recurring [Member] | Guaranteed Minimum Income Benefit
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Market risk benefits	771	[4]	800	[5]
Level 3 | U.S. Treasury / Agency | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	0		0
Level 3 | Debt Security, Government, Non-US [Member] | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	692		564
Level 3 | Corporate securities | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	2,622		2,449
Level 3 | Mortgage-backed securities | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	7		11
Level 3 | States, municipalities, and political subdivisions | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	0		0
Fair Value, Inputs, Level 1, Level 2, and Level 3 | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	106,571		85,220
Equity securities	3,455		827
Short-term investments	4,551		4,960
Other investments	4,825	[1]	951	[2]
Securities lending collateral	1,299		1,523
Investment derivative instruments, assets	54		82
Derivative Instruments in Hedges, Assets, at Fair Value	136		17
Other Derivative Instruments Fair Value			33
Separate account assets	5,573		5,190
Assets, Fair Value Disclosure	126,464	[1],[3]	98,803	[2]
Investment derivative instruments, liability	136		139
Derivative Instruments in Hedges, Liabilities, at Fair Value	128
Other derivative instruments, liability	42		53
Liabilities Related to Investment Contracts, Fair Value Disclosure	1,077		992
Fair Value, Inputs, Level 1, Level 2, and Level 3 | Fair Value, Recurring [Member] | Guaranteed Minimum Income Benefit
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Market risk benefits	771	[4]	800	[5]
Fair Value, Inputs, Level 1, Level 2, and Level 3 | U.S. Treasury / Agency | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	3,590		2,626
Fair Value, Inputs, Level 1, Level 2, and Level 3 | Debt Security, Government, Non-US [Member] | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	35,164		25,908
Fair Value, Inputs, Level 1, Level 2, and Level 3 | Corporate securities | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	42,830		36,955
Fair Value, Inputs, Level 1, Level 2, and Level 3 | Mortgage-backed securities | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	22,058		15,851
Fair Value, Inputs, Level 1, Level 2, and Level 3 | States, municipalities, and political subdivisions | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value	$ 2,929		$ 3,880

[1] Excluded from the table above are other investments of $702 million, principally policy loans at December 31, 2023 measured using NAV as a practical expedient

[2] Excluded from the table above are other investments of $390 million, principally policy loans at December 31, 2022 measured using NAV as a practical expedient. (2)Excluded from the table above are Private equities of $12,355 million at December 31, 2022 measured using NAV as a practical expedient.

[3] Excluded from the table above are Private equities of $14,078 million at December 31, 2023 measured using NAV as a practical expedient.

[4] Refer to Note 11 for additional information on Market risk benefits.

[5] Refer to Note 11 for additional information on Market risk benefits.