Loans and Allowance for Credit Losses - Impaired Loans Average Recorded Investment and Interest Income Recognized (Detail) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2016	Mar. 31, 2015
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 5,957	$ 6,395
Interest Income Recognized	65	69
Commercial [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	670	311
Interest Income Recognized	1	2
Commercial Real Estate [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	326	550
Interest Income Recognized	3	3
Residential Mortgages [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	2,539	2,703
Interest Income Recognized	32	33
Other Retail [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	305	355
Interest Income Recognized	3	4
Credit Card [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	211	233
Interest Income Recognized	1	2
Total Loans, Excluding GNMA and Covered Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	4,051	4,152
Interest Income Recognized	40	44
Covered Loans [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	39	42
Government National Mortgage Association [Member]
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	1,867	2,201
Interest Income Recognized	$ 25	$ 25

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- Definition

Amount of average investment of impaired financing receivables for which there is a related allowance for credit losses.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5212-111524

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=49124121&loc=d3e5258-111524

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- Definition

Amount of interest income, recognized on accrual basis, on financing receivables, for which there is a related allowance for credit losses and are recognized as impaired.

+ References

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