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Derivative Instruments and Hedging Activities - Gains Losses on Freestanding Derivatives (Details) - Other non-interest income - USD ($) $ in Millions | 3 Months Ended
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Mar. 31, 2021 | Mar. 31, 2020
Derivative Instruments, Gain (Loss) [Line Items] |  |
Gains (losses) on derivatives not designated as accounting hedges | $ 30 | $ 50
Interest rate contracts |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Gains (losses) on derivatives not designated as accounting hedges | 19 | 33
Interest rate contracts | Customer accommodation |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Gains (losses) on derivatives not designated as accounting hedges | 10 | 13
Interest rate contracts | Other interest rate exposures |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Gains (losses) on derivatives not designated as accounting hedges | 11 | 18
Commodity contracts | Customer accommodation |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Gains (losses) on derivatives not designated as accounting hedges | 5 | 17
Foreign exchange contracts | Customer accommodation |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Gains (losses) on derivatives not designated as accounting hedges | 4 | 3
Other contracts |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Gains (losses) on derivatives not designated as accounting hedges | $ 0 | $ (1)

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- Definition Amount of realized and unrealized gain (loss) of derivative instruments not designated or qualifying as hedging instruments. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4CC -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL109998890-113959 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4C -Subparagraph (e) -URI http://asc.fasb.org/extlink&oid=121590274&loc=SL5624171-113959 + Details
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