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Loans - Additional Information (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Financing Receivable, Allowance for Credit Loss [Line Items]
Accrued interest receivable	$ 1,200
TDRs	2,100	$ 1,700
Commitments to lend on loans modified in TDRs	173	178
Loans held for sale	2,710	400
Commercial and multifamily real estate
Financing Receivable, Allowance for Credit Loss [Line Items]
Payments for Origination of Mortgage Loans Held-for-sale	10,000	9,000	$ 8,700
Federal Home Loan banks
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans Pledged as Collateral	14,100	14,600
Line of Credit Facility, Remaining Borrowing Capacity	19,600	18,700
Federal Reserve Discount Window
Financing Receivable, Allowance for Credit Loss [Line Items]
Loans Pledged as Collateral	25,500	6,700
Line of Credit Facility, Remaining Borrowing Capacity	20,000	5,300
Credit Card and Consumer Banking | Performing
Financing Receivable, Allowance for Credit Loss [Line Items]
TDRs	1,300	1,100
Commercial Banking | Performing
Financing Receivable, Allowance for Credit Loss [Line Items]
TDRs	442	$ 224
Domestic credit card: | Credit Card
Financing Receivable, Allowance for Credit Loss [Line Items]
Revolving loans converted to term during period	$ 602

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- Definition

Amount, before allowance for credit loss, of accrued interest on financing receivable.

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Amount of financing receivable modified as troubled debt restructuring.

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Amount of increase in term loan from conversion of revolving financing receivable.

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Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

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Amount of unfunded portion of contractual agreement to lend funds to borrower for financing receivable modified as troubled debt restructuring.

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Carrying amount as of the balance sheet date of loans that have been pledged as collateral for borrowings. If the secured party has the right by contract or custom to sell or re-pledge the collateral, then the debtor reclassifies that asset and report that asset in its statement of financial position separately from other assets not so encumbered.

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Amount, after valuation allowance, of financing receivable held for sale and not part of disposal group. Excludes loan covered under loss sharing agreement and loan classified as investment in debt security.

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The amount of cash paid for the origination of mortgages that are held for sale.

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