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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
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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.

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