Fair Value Measurements (Financial Instruments Measured At Fair Value on Recurring Basis) (Details) - USD ($) $ in Millions		Dec. 31, 2024		Dec. 31, 2023
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value		$ 110,363		$ 106,571
Equity securities		9,151		3,455
Short-term investments		5,142		4,551
Other investments		8,597		5,527
Securities lending collateral		1,445		1,299
Separate account assets		6,231		5,573
Market risk benefits		607		771
Reserved alternative investment fund
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Equity securities		4,978
Policy Loans [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Other investments		1,241		702
Investment Funds Limited Partnerships Partially Owned Investment Companies Fair Value [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Other investments		14,769		14,078
U.S. Treasury / Agency
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value		2,341		3,590
Debt Security, Government, Non-US [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value		35,838		35,164
Corporate securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value		43,207		42,830
Mortgage-backed securities
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value		27,248		22,058
States, municipalities, and political subdivisions
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value		1,729		2,929
Level 1 | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value		1,765		2,911
Equity securities		4,053	[1]	3,368
Short-term investments		3,156		1,915
Other investments		573	[2]	589	[3]
Securities lending collateral		0		0
Investment derivative instruments, assets		41		54
Derivative Instruments in Hedges, Assets, at Fair Value		0		0
Other Derivative Instruments Fair Value		35
Separate account assets		6,165		5,482
Assets, Fair Value Disclosure		15,788	[1],[2],[4]	14,319	[3],[5]
Investment derivative instruments, liability		303		136
Derivative Instruments in Hedges, Liabilities, at Fair Value		0		0
Other derivative instruments, liability		0		37
Market risk benefits	[6]	0		0
Liabilities Related to Investment Contracts, Fair Value Disclosure		303		173
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		1,765		2,911
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		105,100		100,339
Equity securities		0	[1]	0
Short-term investments		1,972		2,633
Other investments		6,783	[2]	4,236	[3]
Securities lending collateral		1,445		1,299
Investment derivative instruments, assets		0		0
Derivative Instruments in Hedges, Assets, at Fair Value		146		136
Other Derivative Instruments Fair Value		0
Separate account assets		66		91
Assets, Fair Value Disclosure		115,512	[1],[2],[4]	108,734	[3],[5]
Investment derivative instruments, liability		0		0
Derivative Instruments in Hedges, Liabilities, at Fair Value		116		128
Other derivative instruments, liability		2		5
Market risk benefits	[6]	0		0
Liabilities Related to Investment Contracts, Fair Value Disclosure		118		133
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		576		679
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		35,234		34,472
Level 2 | Corporate securities | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value		40,316		40,208
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		27,245		22,051
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		1,729		2,929
Level 3 | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value		3,498		3,321
Equity securities		120	[1]	87
Short-term investments		14		3
Other investments		0	[2]	0	[3]
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		3,632	[1],[2],[4]	3,411	[3],[5]
Investment derivative instruments, liability		0		0
Derivative Instruments in Hedges, Liabilities, at Fair Value		0		0
Other derivative instruments, liability		0		0
Market risk benefits	[6]	607		771
Liabilities Related to Investment Contracts, Fair Value Disclosure		607		771
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		604		692
Level 3 | Corporate securities | Fair Value, Recurring [Member]
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items]
Available for sale, Fair Value		2,891		2,622
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		3		7
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		110,363		106,571
Equity securities		4,173	[1]	3,455
Short-term investments		5,142		4,551
Other investments		7,356	[2]	4,825	[3]
Securities lending collateral		1,445		1,299
Investment derivative instruments, assets		41		54
Derivative Instruments in Hedges, Assets, at Fair Value		146		136
Other Derivative Instruments Fair Value		35
Separate account assets		6,231		5,573
Assets, Fair Value Disclosure		134,932	[1],[2],[4]	126,464	[3],[5]
Investment derivative instruments, liability		303		136
Derivative Instruments in Hedges, Liabilities, at Fair Value		116		128
Other derivative instruments, liability		2		42
Market risk benefits	[6]	607
Liabilities Related to Investment Contracts, Fair Value Disclosure		1,028		1,077
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	[6]			771
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		2,341		3,590
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		35,838		35,164
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		43,207		42,830
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		27,248		22,058
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		$ 1,729		$ 2,929

[1] Excluded from the table above is a fund of $4,978 million, measured using NAV as a practical expedient.

[2] Excluded from the table above are other investments of $1,241 million, principally policy loans measured using NAV as a practical expedient

[3] Excluded from the table above are other investments of $702 million, principally policy loans measured using NAV as a practical expedient.

[4] Excluded from the table above are private equities of $14,769 million, measured using NAV as a practical expedient.

[5] Excluded from the table above are private equities of $14,078 million, measured using NAV as a practical expedient.

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