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Fair Value Measurements (Financial Instruments Measured At Fair Value On Recurring Basis) (Detail) - USD ($) $ in Millions | Mar. 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 | $ 89,479 |  | $ 93,108 |
Equity securities, at fair value | 3,596 |  | 4,782 |
Short-term investments, at fair value (amortized cost – $3,408 and $3,147) | 3,407 |  | 3,146 |
Other investments, at fair value | 11,947 |  | 11,169 |
Securities lending collateral | 1,800 |  | 1,831 |
U.S. Treasury / Agency |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 2,102 |  | 2,214 |
Non-U.S. |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 24,784 |  | 25,829 |
Corporate and asset-backed securities |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 37,669 |  | 39,063 |
Mortgage-backed securities |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 19,805 |  | 20,489 |
Municipal |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 5,119 |  | 5,513 |
Fair Value, Recurring [Member] | Level 1 |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 1,562 |  | 1,680 |
Equity securities, at fair value | 3,514 |  | 4,705 |
Short-term investments, at fair value (amortized cost – $3,408 and $3,147) | 1,954 |  | 1,744 |
Other investments, at fair value | 253 | [1] | 286 | [2]
Securities lending collateral | 0 |  | 0 |
Investment derivative instruments, assets | 163 |  | 58 |
Other Derivative Instruments Fair Value | 3 |  |  |
Separate Account Asset | 5,468 |  | 5,461 |
Total assets measured at fair value | 12,917 | [1] | 13,934 | [2]
Investment derivative instruments, liabilities | 212 |  | 166 |
Other derivative instruments, liability | 63 |  | 16 |
Liabilities Related to Investment Contracts, Fair Value Disclosure | 275 |  | 182 |
Fair Value, Recurring [Member] | Level 1 | U.S. Treasury / Agency |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 1,562 |  | 1,680 |
Fair Value, Recurring [Member] | Level 1 | Non-U.S. |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 0 |  | 0 |
Fair Value, Recurring [Member] | Level 1 | Corporate and asset-backed securities |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 0 |  | 0 |
Fair Value, Recurring [Member] | Level 1 | Mortgage-backed securities |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 0 |  | 0 |
Fair Value, Recurring [Member] | Level 1 | Municipal |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 0 |  | 0 |
Fair Value, Recurring [Member] | Level 1 | GLB |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross | 0 | [3] | 0 | [4]
Fair Value, Recurring [Member] | Level 2 |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 85,050 |  | 88,720 |
Equity securities, at fair value | 0 |  | 0 |
Short-term investments, at fair value (amortized cost – $3,408 and $3,147) | 1,449 |  | 1,395 |
Other investments, at fair value | 452 | [1] | 481 | [2]
Securities lending collateral | 1,800 |  | 1,831 |
Investment derivative instruments, assets | 0 |  | 0 |
Other Derivative Instruments Fair Value | 0 |  |  |
Separate Account Asset | 92 |  | 99 |
Total assets measured at fair value | 88,843 | [1] | 92,526 | [2]
Investment derivative instruments, liabilities | 0 |  | 0 |
Other derivative instruments, liability | 0 |  | 0 |
Liabilities Related to Investment Contracts, Fair Value Disclosure | 0 |  | 0 |
Fair Value, Recurring [Member] | Level 2 | U.S. Treasury / Agency |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 540 |  | 534 |
Fair Value, Recurring [Member] | Level 2 | Non-U.S. |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 24,166 |  | 25,196 |
Fair Value, Recurring [Member] | Level 2 | Corporate and asset-backed securities |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 35,440 |  | 37,014 |
Fair Value, Recurring [Member] | Level 2 | Mortgage-backed securities |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 19,785 |  | 20,463 |
Fair Value, Recurring [Member] | Level 2 | Municipal |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 5,119 |  | 5,513 |
Fair Value, Recurring [Member] | Level 2 | GLB |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross | 0 | [3] | 0 | [4]
Fair Value, Recurring [Member] | Level 3 |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 2,867 |  | 2,708 |
Equity securities, at fair value | 82 |  | 77 |
Short-term investments, at fair value (amortized cost – $3,408 and $3,147) | 4 |  | 7 |
Other investments, at fair value | 0 | [1] | 0 | [2]
Securities lending collateral | 0 |  | 0 |
Investment derivative instruments, assets | 0 |  | 0 |
Other Derivative Instruments Fair Value | 0 |  |  |
Separate Account Asset | 0 |  | 0 |
Total assets measured at fair value | 2,953 | [1] | 2,792 | [2]
Investment derivative instruments, liabilities | 0 |  | 0 |
Other derivative instruments, liability | 0 |  | 0 |
Liabilities Related to Investment Contracts, Fair Value Disclosure | 696 |  | 745 |
Fair Value, Recurring [Member] | Level 3 | U.S. Treasury / Agency |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 0 |  | 0 |
Fair Value, Recurring [Member] | Level 3 | Non-U.S. |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 618 |  | 633 |
Fair Value, Recurring [Member] | Level 3 | Corporate and asset-backed securities |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 2,229 |  | 2,049 |
Fair Value, Recurring [Member] | Level 3 | Mortgage-backed securities |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 20 |  | 26 |
Fair Value, Recurring [Member] | Level 3 | Municipal |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 0 |  | 0 |
Fair Value, Recurring [Member] | Level 3 | GLB |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross | 696 | [3] | 745 | [4]
Fair Value, Recurring [Member] | Estimate of Fair Value Measurement [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 89,479 |  | 93,108 |
Equity securities, at fair value | 3,596 |  | 4,782 |
Short-term investments, at fair value (amortized cost – $3,408 and $3,147) | 3,407 |  | 3,146 |
Other investments, at fair value | 705 | [1] | 767 | [2]
Securities lending collateral | 1,800 |  | 1,831 |
Investment derivative instruments, assets | 163 |  | 58 |
Other Derivative Instruments Fair Value | 3 |  |  |
Separate Account Asset | 5,560 |  | 5,560 |
Total assets measured at fair value | 104,713 | [1] | 109,252 | [2]
Investment derivative instruments, liabilities | 212 |  | 166 |
Other derivative instruments, liability | 63 |  | 16 |
Liabilities Related to Investment Contracts, Fair Value Disclosure | 971 |  | 927 |
Fair Value, Recurring [Member] | Estimate of Fair Value Measurement [Member] | U.S. Treasury / Agency |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 2,102 |  | 2,214 |
Fair Value, Recurring [Member] | Estimate of Fair Value Measurement [Member] | Non-U.S. |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 24,784 |  | 25,829 |
Fair Value, Recurring [Member] | Estimate of Fair Value Measurement [Member] | Corporate and asset-backed securities |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 37,669 |  | 39,063 |
Fair Value, Recurring [Member] | Estimate of Fair Value Measurement [Member] | Mortgage-backed securities |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 19,805 |  | 20,489 |
Fair Value, Recurring [Member] | Estimate of Fair Value Measurement [Member] | Municipal |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Available for sale, Fair Value | 5,119 |  | 5,513 |
Fair Value, Recurring [Member] | Estimate of Fair Value Measurement [Member] | GLB |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Liabilities for Guarantees on Long-Duration Contracts, Guaranteed Benefit Liability, Gross | 696 | [3] | 745 | [4]
Investment Funds Limited Partnerships Partially Owned Investment Companies Fair Value [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Other investments, at fair value | 10,947 |  | 10,108 |
Policy Loans [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Other investments, at fair value | 244 |  | 243 |
Other Investments [Member] |  |  |  |
Fair Value Assets And Liabilities Measured On Recurring Basis [Line Items] |  |  |  |
Other investments, at fair value | $ 51 |  | $ 51 |
[1] | Excluded from the table above are partially-owned investments, investment funds, and limited partnerships of $10,947 million, policy loans of $244 million and other investments of $51 million at March 31, 2022 measured using NAV as a practical expedient.
[2] | Excluded from the table above are partially-owned investments, investment funds, and limited partnerships of $10,108 million, policy loans of $243 million and other investments of $51 million at December 31, 2021 measured using NAV as a practical expedient.
[3] | Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value.
[4] | Our GLB reinsurance product meets the definition of a derivative instrument for accounting purposes and is accordingly carried at fair value.

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