Loans - By Portfolio Segment (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Loan balances by portfolio segment:
Retained loans	$ 974,260	$ 945,537	$ 974,260	$ 945,537	$ 960,506
Held-for-sale	9,727		9,727		7,873
At fair value	60,628		60,628		44,474
Total	1,044,615		1,044,615		1,012,853
Accrued interest receivables	2,700		2,700		2,900
Accrued interest receivables written off	10	34	30	82
Consumer, excluding credit card
Loan balances by portfolio segment:
Retained loans	298,308	305,106	298,308	305,106	302,127
Held-for-sale	1,407		1,407		1,305
At fair value	28,449		28,449		15,147
Total	328,164		328,164		318,579
Credit card
Loan balances by portfolio segment:
Retained loans	143,166		143,166		143,432
Held-for-sale	0		0		784
At fair value	0		0		0
Total	143,166		143,166		144,216
Wholesale
Loan balances by portfolio segment:
Retained loans	532,786	$ 500,841	532,786	$ 500,841	514,947
Held-for-sale	8,320		8,320		5,784
At fair value	32,179		32,179		29,327
Total	$ 573,285		$ 573,285		$ 550,058

Financing Receivable, Excluding Accrued Interest, Before Allowance For Credit Losses, Net of Deferred Income

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

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

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Fair value portion of loan receivable, including, but not limited to, mortgage loans held for investment, finance receivables held for investment, policy loans on insurance contracts.

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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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