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Investments (Net Realized Gains (Losses) And Losses Included In Net Realized Gains (Losses) And Other Comprehensive Income) (Detail) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
--- | --- | ---
Jun. 30, 2021 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
Realized Investment Gains (Losses) | $ (33) |  | $ 30 |  | $ 854 |  | $ (928)
Foreign exchange gains | (97) |  | (61) |  | (21) |  | (129)
Insurance Derivatives, Changes in Fair Value, Gain (Loss) | (8) |  | 213 |  | 311 |  | (472)
Gain (Loss) on Derivative | (160) |  | 123 |  | 223 |  | (424)
Other | 0 |  | (40) |  | (1) |  | (40)
Fixed Maturities [Member] |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
Debt Securities, Available-for-sale, Realized Gain | 56 |  | 68 |  | 93 |  | 145
Debt Securities, Available-for-sale, Realized Loss | (53) |  | (174) |  | (72) |  | (299)
Debt Securities, Allowance for Credit Loss, Period Increase (Decrease) | 10 |  | 104 |  | 16 |  | (46)
Debt Securities, Available-For-Sale, Credit Impairment Charges Intent to Sell | (1) | [1] | (31) | [1] | (1) | [1] | (152)
Debt Securities, Available-for-sale, Realized Gain (Loss) | 12 |  | (33) |  | 36 |  | (352)
Equity Securities [Member] |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
Equity Securities, FV-NI, Realized Gain (Loss) | 150 |  | 148 |  | 517 |  | 119
Other Investments [Member] |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
Realized Investment Gains (Losses) | 62 |  | (107) |  | 100 |  | (102)
Other derivative instruments |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
Gain (Loss) on Derivative | 3 |  | (1) |  | 2 |  | (3)
Investment and embedded derivative instruments |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
Gain (Loss) on Derivative | (91) |  | 14 |  | 18 |  | 29
S&P put options and futures |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
Gain (Loss) on Derivative | (64) |  | (103) |  | (108) |  | 22
Accounting Standards Update 2016-13 [Member] |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
Debt Securities, Allowance for Credit Loss, Period Increase (Decrease) | $ 1 |  | $ 29 |  | $ 5 |  | $ 178
[1] | Relates to certain securities we intended to sell and securities written to market entering default.

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