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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
--- | ---
Mar. 31, 2019 | Mar. 31, 2018
Gain (Loss) on Securities [Line Items] |  |
OTTI on fixed maturities, gross and net | $ 13 | $ 1
Foreign exchange gains (losses) | 13 | (77)
Gain (Loss) on Derivative | (80) | 79
Fair Value Adjustments On Insurance Derivative Gains Losses | 114 | 38
Net Realized Gains (Losses) | (97) | (2)
Investment and embedded derivative instruments |  |
Gain (Loss) on Securities [Line Items] |  |
Gain (Loss) on Derivative | (130) | 17
S&P put options and futures |  |
Gain (Loss) on Securities [Line Items] |  |
Gain (Loss) on Derivative | (63) | 22
Other derivative instruments |  |
Gain (Loss) on Securities [Line Items] |  |
Gain (Loss) on Derivative | (1) | 2
Fixed Maturities [Member] |  |
Gain (Loss) on Securities [Line Items] |  |
OTTI on fixed maturities, gross and net | (13) | (1)
Debt Securities, Available-for-sale, Realized Gain (Loss), Excluding Other-than-temporary Impairment | 27 | 66
Debt Securities, Available-for-sale, Realized Loss, Excluding Other-than-temporary Impairment | (58) | (88)
Debt Securities, Available-for-sale, Realized Gain (Loss) | (44) | (23)
Equity Securities [Member] |  |
Gain (Loss) on Securities [Line Items] |  |
Equity Securities, FV-NI, Realized Gain | 64 | 10
Equity Securities, FV-NI, Realized Loss | (6) | (21)
Equity Securities, FV-NI, Realized Gain (Loss) | 58 | (11)
Other Investments [Member] |  |
Gain (Loss) on Securities [Line Items] |  |
Other investments gain (loss) | (44) | 29
Other [Member] |  |
Gain (Loss) on Securities [Line Items] |  |
Other | $ 0 | $ 1

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