Credit Quality (Summary of Average Impaired Loans and Leases and Interest Income by Class) (Detail) - USD ($) $ in Millions	12 Months Ended
Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Financing Receivable, Impaired
Average Recorded Investment	$ 1,393	$ 1,469	$ 1,677
Interest Income Recognized	53	60	52
Commercial Portfolio Segment \| Commercial and Industrial Loans
Financing Receivable, Impaired
Average Recorded Investment	306	373	579
Interest Income Recognized	7	15	10
Commercial Portfolio Segment \| Commercial Mortgage Loans, Owner-Occupied
Financing Receivable, Impaired
Average Recorded Investment	23	15	35
Interest Income Recognized	0	0	0
Commercial Portfolio Segment \| Commercial Mortgage Loans, Nonowner-Occupied
Financing Receivable, Impaired
Average Recorded Investment	8	24	61
Interest Income Recognized	0	0	1
Commercial Portfolio Segment \| Commercial Leases
Financing Receivable, Impaired
Average Recorded Investment	28	18	3
Interest Income Recognized	1	0	0
Residential Mortgage Loans
Financing Receivable, Impaired
Average Recorded Investment	756	743	657
Interest Income Recognized	30	28	25
Consumer Portfolio Segment \| Home Equity
Financing Receivable, Impaired
Average Recorded Investment	221	244	281
Interest Income Recognized	11	12	12
Consumer Portfolio Segment \| Indirect secured consumer loans
Financing Receivable, Impaired
Average Recorded Investment	7	8	11
Interest Income Recognized	0	0	0
Consumer Portfolio Segment \| Credit Card
Financing Receivable, Impaired
Average Recorded Investment	44	44	50
Interest Income Recognized	$ 4	$ 5	$ 4

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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=118936363&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=118936363&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.

+ References

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