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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 | 9 Months Ended
--- | --- | ---
Sep. 30, 2020 | Sep. 30, 2019 | Sep. 30, 2020 | Sep. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative |  | $ 4 | $ (223) | $ (420) | $ (562)
Foreign currency forward contracts |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative |  | 0 | (20) | 53 | (57)
Interest Rate Swap [Member] |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative |  | 0 | (55) | 0 | (270)
All Other Futures Contracts, Options and equities [Member] |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative |  | 9 | (22) | (15) | (83)
Convertible securities |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative | [1] | 0 | 0 | 0 | 2
Total investment and embedded derivative instruments |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative |  | 9 | (97) | 38 | (408)
GLB |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative | [2] | 46 | (106) | (426) | (57)
Futures contracts on equities |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative | [3] | (52) | (6) | (30) | (89)
Other |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative |  | 1 | (14) | (2) | (8)
Guaranteed Living Benefit And Other Derivative Instruments [Member] |  |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |  |
Gain (Loss) on Derivative |  | $ (5) | $ (126) | $ (458) | $ (154)
[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=121590274&loc=SL5618551-113959 + Details
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