Credit Quality (Summary of Average Impaired Loans and Leases and Interest Income by Class) (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Financing Receivable, Impaired
Average Recorded Investment	$ 1,430	$ 1,660	$ 1,513	$ 1,738
Interest Income Recognized	14	14	46	37
Commercial Portfolio Segment \| Commercial and Industrial Loans
Financing Receivable, Impaired
Average Recorded Investment	313	581	408	611
Interest Income Recognized	3	4	13	6
Commercial Portfolio Segment \| Commercial Mortgage Loans, Owner-occupied
Financing Receivable, Impaired
Average Recorded Investment	11	50	17	55
Interest Income Recognized	0	0	0	0
Commercial Portfolio Segment \| Commercial Mortgage Loans, Nonowner-Occupied
Financing Receivable, Impaired
Average Recorded Investment	21	40	27	69
Interest Income Recognized	0	0	0	1
Commercial Portfolio Segment \| Commercial Leases
Financing Receivable, Impaired
Average Recorded Investment	28	1	17	2
Interest Income Recognized	0	0	0	0
Residential Mortgage Loans
Financing Receivable, Impaired
Average Recorded Investment	767	654	744	655
Interest Income Recognized	7	6	21	18
Consumer Portfolio Segment \| Home Equity
Financing Receivable, Impaired
Average Recorded Investment	239	275	248	285
Interest Income Recognized	3	3	9	9
Consumer Portfolio Segment \| Automobile Loans
Financing Receivable, Impaired
Average Recorded Investment	7	11	8	12
Interest Income Recognized	0	0	0	0
Consumer Portfolio Segment \| Credit Card
Financing Receivable, Impaired
Average Recorded Investment	44	48	44	49
Interest Income Recognized	$ 1	$ 1	$ 3	$ 3

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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.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-Subparagraph (c)(1)
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 17
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5258-111524

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Amount of interest income recognized that the financing receivables (with related allowance for credit losses and without a related allowance for credit losses) were impaired.

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