Credit Quality and the Allowance for Loan and Lease Losses - Summary of Subsequent Defaults (Details) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020 USD ($) contract	Jun. 30, 2019 USD ($) contract	Jun. 30, 2020 USD ($) contract	Jun. 30, 2019 USD ($) contract
Financing Receivable, Modifications
Number of Contracts \| contract	58	314	313	679
Amortized Cost \| $	$ 13	$ 11	$ 26	$ 41
Commercial \| Commercial and industrial loans
Financing Receivable, Modifications
Number of Contracts \| contract	6	5	6	7
Amortized Cost \| $	$ 4	$ 1	$ 4	$ 17
Commercial \| Commercial mortgage owner-occupied loans
Financing Receivable, Modifications
Number of Contracts \| contract	5	2	7	2
Amortized Cost \| $	$ 1	$ 1	$ 2	$ 1
Commercial \| Commercial mortgage nonowner-occupied loans
Financing Receivable, Modifications
Number of Contracts \| contract	1		2
Amortized Cost \| $	$ 4		$ 9
Residential Mortgage
Financing Receivable, Modifications
Number of Contracts \| contract	25	53	72	129
Amortized Cost \| $	$ 4	$ 8	$ 10	$ 20
Consumer \| Home equity
Financing Receivable, Modifications
Number of Contracts \| contract	2	1	3	5
Amortized Cost \| $	$ 0	$ 0	$ 0	$ 0
Consumer \| Indirect secured consumer loans
Financing Receivable, Modifications
Number of Contracts \| contract	3		6
Amortized Cost \| $	$ 0		$ 0
Consumer \| Credit card
Financing Receivable, Modifications
Number of Contracts \| contract	16	253	217	536
Amortized Cost \| $	$ 0	$ 1	$ 1	$ 3

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Number of financing receivable contracts modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953682-111524

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Amount of financing receivable modified as troubled debt restructuring within previous 12 months, with subsequent payment default.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 34
-Subparagraph (a)(2)
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953682-111524

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