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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, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
OTTI on fixed maturities, gross | $ 0 |  | $ (14) |  | $ 0 |  | $ (27)
Debt Securities, Allowance for Credit Loss, Period Increase (Decrease) | 29 |  |  |  | 178 |  |
Debt Securities, Available-For-Sale, Credit Impairment Charges Intent to Sell | (31) | [1] | 0 | [1] | (152) | [1] | 0
Foreign exchange gains | (61) |  | (11) |  | (129) |  | 2
Gain (Loss) on Derivative | 123 |  | (259) |  | (424) |  | (339)
Other | (40) |  | 0 |  | (40) |  | 0
Net Realized Gains (Losses) | 30 |  | (223) |  | (928) |  | (320)
Other than Temporary Impairment Loss, Investments, Portion in Other Comprehensive Loss, before Tax, Portion Attributable to Parent, Available-for-sale Securities | 0 |  | 1 |  | 0 |  | 1
Other-than-temporary Impairment Loss, Debt Securities, Portion Recognized in Earnings | 0 |  | (13) |  | 0 |  | (26)
Fair Value, Option, Changes in Fair Value, Gain (Loss) | 213 |  | (65) |  | (472) |  | 49
Other than Temporary Impairment Losses, Investments, Portion in Other Comprehensive Loss, before Tax, Portion Attributable to Parent | 0 |  | 1 |  |  |  | 1
Investment and embedded derivative instruments |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
Gain (Loss) on Derivative | 14 |  | (181) |  | 29 |  | (311)
S&P put options and futures |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
Gain (Loss) on Derivative | (103) |  | (20) |  | 22 |  | (83)
Other derivative instruments |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
Gain (Loss) on Derivative | (1) |  | 7 |  | (3) |  | 6
Fixed Maturities [Member] |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
OTTI on fixed maturities, gross |  |  | 14 |  | 0 |  | 27
Debt Securities, Available-for-sale, Realized Gain, Excluding Other-than-temporary Impairment | 68 |  | 56 |  | 145 |  | 83
Debt Securities, Available-for-sale, Realized Loss, Excluding Other-than-temporary Impairment | (174) |  | (31) |  | (299) |  | (89)
Debt Securities, Available-for-sale, Realized Gain (Loss) | (33) |  | 12 |  | (352) |  | (32)
Debt Securities [Member] |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
Other-than-temporary Impairment Loss, Debt Securities, Portion Recognized in Earnings |  |  | (13) |  | 0 |  | (26)
Equity Securities [Member] |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
Equity Securities, FV-NI, Realized Gain (Loss) | 148 |  | 5 |  | 119 |  | 63
Other Investments [Member] |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
Other investments gain (loss) | (107) |  | 30 |  | (102) |  | (14)
Accounting Standards Update 2016-13 [Member] |  |  |  |  |  |  |
Gain (Loss) on Securities [Line Items] |  |  |  |  |  |  |
Debt Securities, Allowance for Credit Loss, Period Increase (Decrease) | $ 104 |  | $ 0 |  | $ (46) |  | $ 0
[1] | Relates to certain securities we intended to sell and securities written to market entering default.

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