Loans - Consumer, Excluding Credit Card Loan Portfolio, Other Consumer Impaired Loans and Loan Modifications (Details) - Consumer, excluding credit card - Other consumer - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Dec. 31, 2018
Financing Receivable, Impaired [Line Items]
With an allowance	$ 242		$ 242		$ 222
Without an allowance	20		20		29
Total impaired loans	262		262		251
Allowance for loan losses related to impaired loans	68		68		63
Unpaid principal balance of impaired loans	357		357		355
Impaired loans on nonaccrual status	240		240		229
Average impaired loans	254	$ 271	248	$ 281
Loans modified in TDRs	77		77		79
TDRs on nonaccrual status	$ 55		$ 55		$ 57

Financing Receivable, Modifications, Recorded Investment, Nonaccrual Status

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Impaired Financing Receivable, Recorded Investment, Nonaccrual Status

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Amount of financing receivable modified as troubled debt restructuring.

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-Publisher FASB
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Average amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

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Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without related allowance for credit losses.

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Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

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