Loans and Leases (Narrative) (Detail) $ in Millions	3 Months Ended	12 Months Ended
Dec. 31, 2015 USD ($) grade	Dec. 31, 2015 USD ($) grade	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Loans and Leases Receivable Disclosure [Abstract]
Pledged Financial Instruments, Not Separately Reported, Loans Receivable Pledged as Collateral	$ 6,100.0	$ 6,100.0
Interest on non-accrual loans that would have been recorded as additional interest income	$ 8.2		$ 9.3	$ 11.4
Number of Grades \| grade	10	10
Write-down of TDR's		$ (11.8)	$ (13.5)	$ (24.4)

Reflects the amount of the write-down related to a troubled debt restructuring.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 4
-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18845-111554

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- References

No definition available.

+ Details

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- Definition

Reflects the amount of additional interest income that would have been recorded if impaired or nonperforming loans were instead current, in compliance with their original terms, and outstanding throughout the reporting period or since origination (if held for part of the period).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 40
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18794-111554

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- Definition

The sum of the carrying amounts, as of the date of the latest financial statement presented, of loans receivable which are owned but transferred to serve as collateral for the payment of related debt obligations, primarily secured borrowings and repurchase agreements, and for which the transferees are not permitted to sell or re-pledge them to an unrelated party.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 860
-SubTopic 30
-Section 50
-Paragraph 1A
-Subparagraph (b)(1)(i)
-URI http://asc.fasb.org/extlink&oid=55761124&loc=SL6224234-111729

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- Definition

Number of Grades

+ References

No definition available.

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