Loans and Leases (Troubled Debt Restructurings) (Details) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2020 USD ($) contract	Sep. 30, 2019 USD ($) contract	Sep. 30, 2020 USD ($) contract	Sep. 30, 2019 USD ($) contract
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES \| contract	11	5	19	34
RECORDED INVESTMENT	$ 18.4	$ 3.1	$ 43.6	$ 28.2
UNPAID PRINCIPAL BALANCE	$ 18.5	$ 3.1	$ 44.2	$ 29.6
COMMERCIAL
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES \| contract	1	0	3	3
RECORDED INVESTMENT	$ 1.0	$ 0.0	$ 25.3	$ 7.6
UNPAID PRINCIPAL BALANCE	$ 1.0	$ 0.0	$ 25.5	$ 8.8
COMMERCIAL \| Commercial and Institutional
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES \| contract	1	0	3	1
RECORDED INVESTMENT	$ 1.0	$ 0.0	$ 25.3	$ 7.6
UNPAID PRINCIPAL BALANCE	$ 1.0	$ 0.0	$ 25.5	$ 8.8
COMMERCIAL \| Commercial Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES \| contract		0		2
RECORDED INVESTMENT		$ 0.0		$ 0.0
UNPAID PRINCIPAL BALANCE		$ 0.0		$ 0.0
Personal
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES \| contract	10	5	16	31
RECORDED INVESTMENT	$ 17.4	$ 3.1	$ 18.3	$ 20.6
UNPAID PRINCIPAL BALANCE	$ 17.5	$ 3.1	$ 18.7	$ 20.8
Personal \| Residential Real Estate
Financing Receivable, Troubled Debt Restructuring [Line Items]
NUMBER OF LOANS AND LEASES \| contract	10	5	16	31
RECORDED INVESTMENT	$ 17.4	$ 3.1	$ 18.3	$ 20.6
UNPAID PRINCIPAL BALANCE	$ 17.5	$ 3.1	$ 18.7	$ 20.8

Financing Receivable, Troubled Debt Restructuring, Postmodification, Unpaid Principal Balance

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 33
-URI http://asc.fasb.org/extlink&oid=121611835&loc=SL6953676-111524

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- Definition

Amount, after troubled debt restructuring, of modified financing receivable.

+ References

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