Amount of increase (decrease) of allowance reserve for credit loss.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03.7(d))
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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

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Amount of financing receivable modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=SL6953682-111524

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Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=118936363&loc=d3e5212-111524

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Loans and ACL - Narrative (Details) - USD ($) $ in Millions		3 Months Ended		12 Months Ended
Loans and ACL - Narrative (Details) - USD ($) $ in Millions	Jan. 01, 2020	Mar. 31, 2020	Mar. 31, 2019	Dec. 31, 2019
Receivables [Abstract]
Modifications that defaulted during the period that had been classified as a TDR during the previous 12 months		$ 21	$ 18
Financing Receivable
Interest Income Recognized		8		$ 98
CECL impact on Allowance for Credit Losses
Financing Receivable
Allowance for Loan and Lease Losses, Period Increase (Decrease)	$ 3,100
Commercial:
Financing Receivable
Allowance for Loan and Lease Losses, Period Increase (Decrease)		411
Credit card
Financing Receivable
Allowance for Loan and Lease Losses, Period Increase (Decrease)		50
Interest Income Recognized				$ 1
Credit card \| CECL impact on Allowance for Credit Losses
Financing Receivable
Allowance for Loan and Lease Losses, Period Increase (Decrease)		175
Commitments to extend, originate or purchase credit
Financing Receivable
Allowance for Loan and Lease Losses, Period Increase (Decrease)		(9)
Commitments to extend, originate or purchase credit \| CECL impact on Allowance for Credit Losses
Financing Receivable
Allowance for Loan and Lease Losses, Period Increase (Decrease)		33
Consumer:
Financing Receivable
Allowance for Loan and Lease Losses, Period Increase (Decrease)		$ 130