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Loans - Additional Information (Detail) - USD ($) $ in Millions | 12 Months Ended
--- | ---
Dec. 31, 2019 | Dec. 31, 2018 | Dec. 31, 2017
Loans and Leases Receivable Disclosure [Line Items] |  |  |
Financing Receivable, Troubled Debt Restructuring, Commitment to Lend | $ 178 | $ 256 |
Uncollectible Portion of Billed Finance Charges and Fees | 1,400 | 1,300 | $ 1,400
Finance Charge And Fees Reserves | 462 | 468 |
Loans held for sale | 400 | 1,192 |
Performing |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |
Troubled debt restructurings included in impaired loans | 1,700 | 1,600 |
Commercial Multifamily Real Estate |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |
Payments for Origination of Mortgage Loans Held-for-sale | 9,000 | 8,700 |
Residential Mortgage Loans and Commercial Multifamily Real Estate Loans |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |
Payments for Origination of Mortgage Loans Held-for-sale |  |  | $ 8,400
Federal Home Loan banks |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |
Loans Pledged as Collateral | 14,600 | 15,800 |
Line of Credit Facility, Remaining Borrowing Capacity | 18,700 | 19,300 |
Federal Reserve Discount Window |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |
Loans Pledged as Collateral | 6,700 | 9,200 |
Line of Credit Facility, Remaining Borrowing Capacity | 5,300 | 7,600 |
Consumer Banking | Performing |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |
Troubled debt restructurings included in impaired loans | 1,100 | 1,200 |
Commercial Banking | Performing |  |  |
Loans and Leases Receivable Disclosure [Line Items] |  |  |
Troubled debt restructurings included in impaired loans | $ 224 | $ 282 |

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