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Loans - Additional Information (Details) - USD ($) $ in Millions | 3 Months Ended | 6 Months Ended |
--- | --- | --- | ---
Jun. 30, 2021 | Jun. 30, 2020 | Jun. 30, 2021 | Jun. 30, 2020 | Dec. 31, 2020
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |
Accrued interest receivable | $ 1,200 |  | $ 1,200 |  | $ 1,200
TDRs | 1,800 |  | 1,800 |  | 2,100
Commitments to lend on loans modified in TDRs | 173 |  | 173 |  | 173
Federal Home Loan banks |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |
Loans Pledged as Collateral | 11,600 |  | 11,600 |  | 14,100
Line of Credit Facility, Remaining Borrowing Capacity | 19,200 |  | 19,200 |  | 19,600
Federal Reserve Discount Window |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |
Loans Pledged as Collateral | 26,900 |  | 26,900 |  | 25,500
Line of Credit Facility, Remaining Borrowing Capacity | 21,300 |  | 21,300 |  | 20,000
Credit Card and Consumer Banking | Performing |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |
TDRs | 1,200 |  | 1,200 |  | 1,300
Commercial Banking | Performing |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |
TDRs | 243 |  | 243 |  | $ 442
Domestic credit card: | Credit Card |  |  |  |  |
Financing Receivable, Allowance for Credit Loss [Line Items] |  |  |  |  |
Revolving loans converted to term during period | $ 38 | $ 89 | $ 135 | $ 249 |

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- Definition Amount of financing receivable modified as troubled debt restructuring. + 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=121611835&loc=SL6953676-111524 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 310 -SubTopic 40 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=121585226&loc=d3e18845-111554 + Details
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