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Derivative Instruments and Hedging Activities (Statement of Gains and Losses on Derivative Instruments Reported in Statement of Comprehensive Income) (Details) - Not designated as hedging instrument - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
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Jun. 30, 2020 | Jun. 30, 2019 | Jun. 30, 2020 | Jun. 30, 2019
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (loss) on derivative instruments, net, pretax | $ (28) | $ (4) | $ (35) | $ (9)
Interest rate contracts |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (loss) on derivative instruments, net, pretax | (23) | (2) | (38) | (6)
Foreign exchange contracts |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (loss) on derivative instruments, net, pretax | (5) | (2) | 3 | (3)
Gains on mortgage and automotive loans | Interest rate contracts |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (loss) on derivative instruments, net, pretax | 0 | 0 | (15) | 1
Other income, net of losses | Interest rate contracts |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (loss) on derivative instruments, net, pretax | (23) | (2) | (23) | (7)
Other income, net of losses | Foreign exchange contracts |  |  |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |  |  |
Gain (loss) on derivative instruments, net, pretax | $ (5) | $ (2) | $ 3 | $ (3)

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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- Definition Aggregate net gain (loss) on all derivative instruments recognized in earnings during the period, before tax effects. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 815 -SubTopic 10 -Section 50 -Paragraph 4A -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=109980867&loc=SL5618551-113959 + Details
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