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Derivatives - Gains/(Losses) on Derivatives Associated with Mortgage Banking Hedges (Details) - Mortgage Banking Hedges - Hedged Items - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended
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Jun. 30, 2021 | Jun. 30, 2021
Option contracts written |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Gain (loss) on derivative instruments | $ 1 | $ (9)
Forward contracts purchased |  |
Derivative Instruments, Gain (Loss) [Line Items] |  |
Gain (loss) on derivative instruments | $ (11) | $ 12

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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=125515794&loc=SL5618551-113959 + Details
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