Credit Quality - Summary of Average Impaired Loans and Leases and Interest Income by Class (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	$ 1,401	$ 1,430	$ 1,361	$ 1,513
Interest Income Recognized	13	14	41	46
Commercial Portfolio Segment \| Commercial and Industrial Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	329	313	294	408
Interest Income Recognized	2	3	6	13
Commercial Portfolio Segment \| Commercial Mortgage Loans, Owner-occupied
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	26	11	22	17
Interest Income Recognized	0	0	0	0
Commercial Portfolio Segment \| Commercial Mortgage Loans, Nonowner-Occupied
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	5	21	9	27
Interest Income Recognized	0	0	0	0
Commercial Portfolio Segment \| Commercial Leases
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	33	28	28	17
Interest Income Recognized	0	0	1	0
Residential Mortgage Loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	751	767	742	744
Interest Income Recognized	7	7	22	21
Consumer Portfolio Segment \| Home Equity
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	209	239	217	248
Interest Income Recognized	3	3	9	9
Consumer Portfolio Segment \| Indirect secured consumer loans
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	5	7	6	8
Interest Income Recognized	0	0	0	0
Consumer Portfolio Segment \| Credit Card
Financing Receivable, Impaired [Line Items]
Average Recorded Investment	43	44	43	44
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=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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