Loans - By Portfolio Segment (Details) $ in Millions	9 Months Ended
Sep. 30, 2018 USD ($) loan_segment	Dec. 31, 2017 USD ($)	Sep. 30, 2017 USD ($)
Receivables [Abstract]
Number of portfolio segments \| loan_segment	3
Loan balances by portfolio segment:
Retained loans	$ 947,651	$ 924,838	$ 909,182
Held-for-sale	3,680	3,351
At fair value	2,987	2,508
Total	954,318	930,697
Consumer, excluding credit card
Loan balances by portfolio segment:
Retained loans	375,958	372,553	369,413
Held-for-sale	104	128
At fair value	0	0
Total	376,062	372,681
Credit card
Loan balances by portfolio segment:
Retained loans	147,856	149,387
Held-for-sale	25	124
At fair value	0	0
Total	147,881	149,511
Wholesale
Loan balances by portfolio segment:
Retained loans	423,837	402,898	$ 398,569
Held-for-sale	3,551	3,099
At fair value	2,987	2,508
Total	$ 430,375	$ 408,505

Loans Receivable, Net of Deferred Income

No definition available.

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- Definition

Number of Loan Portfolio Segments

+ References

No definition available.

+ Details

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- Definition

Amount before allowance and after deduction of deferred interest and fees, unamortized costs and premiums and discounts from face amounts, of loans and leases held in portfolio, including but not limited to, commercial and consumer loans. Excludes loans and leases covered under loss sharing agreements.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 45
-Paragraph 2
-URI http://asc.fasb.org/extlink&oid=82891408&loc=d3e4428-111522

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5074-111524

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- Definition

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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-URI http://asc.fasb.org/subtopic&trid=2196772

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- Definition

Amount, after allowance for bad debt, of loan receivables held-for-sale that are not part of a disposal group. Excludes loans and leases covered under loss sharing agreements and loans classified as debt securities.

+ References

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- References

No definition available.

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- References

No definition available.

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