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Commitments, Contingencies, And Guarantees (Net Realized Gains (Losses) Of Derivative Instrument Activity In Consolidated Statement Of Operations) (Detail) - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2020 | Mar. 31, 2019
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) on Derivative |  | $ (547) | $ (80)
Foreign currency forward contracts |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) on Derivative |  | 43 | (15)
Interest Rate Swap [Member] |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) on Derivative |  | 0 | (80)
All Other Futures Contracts, Options and equities [Member] |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) on Derivative |  | (27) | (36)
Convertible securities |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) on Derivative | [1] | (1) | 1
Total investment and embedded derivative instruments |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) on Derivative |  | 15 | (130)
GLB |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) on Derivative | [2] | (685) | 114
Futures contracts on equities |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) on Derivative | [3] | 125 | (63)
Other |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) on Derivative |  | (2) | (1)
Guaranteed Living Benefit And Other Derivative Instruments [Member] |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |
Gain (Loss) on Derivative |  | $ (562) | $ 50
[1] | Includes embedded derivatives.
[2] | Excludes foreign exchange gains (losses) related to GLB.
[3] | Related to GMDB and GLB book of business.

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- Definition Amount of increase (decrease) in the fair value of derivatives recognized in the income statement. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b)(1) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959 + Details
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