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Loans and Allowances for Credit Losses, Troubled Debt Restructurings (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2019 | Jun. 30, 2018 | Jun. 30, 2019 | Jun. 30, 2018 | Dec. 31, 2018
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |
Troubled Debt Restructuring, Recorded Investment | $ 169 |  | $ 169 |  | $ 166
Troubled Debt Restructuring, Performing in Accordance With Modified Terms | 70 |  | 70 |  | 71
Financing Receivable, Troubled Debt Restructuring, Postmodification | 21 | $ 19 | 38 | $ 32 |
Permanent mortgages guaranteed by US government agencies [Member] | Accruing [Member] | Residential mortgage [Member] |  |  |  |  |
Financing Receivable, Troubled Debt Restructuring [Line Items] |  |  |  |  |
Troubled Debt Restructuring, Recorded Investment | $ 96 |  | $ 96 |  | $ 86

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- Definition Represents the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructuring and are performing according to modified terms. + References No definition available. + Details
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- Definition Amount, after troubled debt restructuring, of modified financing receivable. + References Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 10 -Section 50 -Paragraph 33 -URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953676-111524 + Details
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