Loans and Leases (Information on How Loans and Leases were Modified as a TDR) (Detail) $ in Thousands		3 Months Ended		6 Months Ended
		Jun. 30, 2017 USD ($) loan	Jun. 30, 2016 USD ($) loan	Jun. 30, 2017 USD ($) loan	Jun. 30, 2016 USD ($) loan
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		44	53	116	95
Post-Modification Recorded Investment | $	[1]	$ 14,073	$ 4,808	$ 22,727	$ 23,780
Residential Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		4	2	9	7
Post-Modification Recorded Investment | $	[1]	$ 420	$ 338	$ 1,390	$ 1,002
Residential Portfolio Segment [Member] | Adjusted Interest Rate [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		2	0	2	1
Post-Modification Recorded Investment | $	[1]	$ 335	$ 0	$ 335	$ 236
Residential Portfolio Segment [Member] | Maturity/Rate Combined [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		2	7	5	7
Post-Modification Recorded Investment | $	[1]	$ 354	$ 895	$ 846	$ 895
Residential Portfolio Segment [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	[2]	7	8	26	15
Post-Modification Recorded Investment | $	[1],[2]	$ 1,176	$ 1,476	$ 4,114	$ 2,891
Consumer Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		4	6	6	7
Post-Modification Recorded Investment | $	[1]	$ 625	$ 193	$ 664	$ 292
Consumer Portfolio Segment [Member] | Maturity/Rate Combined [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		4	4	11	8
Post-Modification Recorded Investment | $	[1]	$ 830	$ 359	$ 2,813	$ 659
Consumer Portfolio Segment [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	[2]	10	22	43	29
Post-Modification Recorded Investment | $	[1],[2]	$ 701	$ 839	$ 2,894	$ 1,177
Commercial Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		6	0	8	9
Post-Modification Recorded Investment | $	[1]	$ 778	$ 0	$ 813	$ 14,649
Commercial Portfolio Segment [Member] | Maturity/Rate Combined [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		5	1	5	2
Post-Modification Recorded Investment | $	[1]	$ 8,854	$ 644	$ 8,854	$ 648
Commercial Portfolio Segment [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	[2]	0	3	1	7
Post-Modification Recorded Investment | $	[1],[2]	$ 0	$ 64	$ 4	$ 374
Commercial Real Estate Portfolio Segment [Member] | Maturity/Rate Combined [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		0	0	0	1
Post-Modification Recorded Investment | $	[1]	$ 0	$ 0	$ 0	$ 444
Commercial Real Estate Portfolio Segment [Member] | Other [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan	[2]	0	0	0	1
Post-Modification Recorded Investment | $	[1],[2]	$ 0	$ 0	$ 0	$ 509
Finance Leases Portfolio Segment [Member] | Extended Maturity [Member]
Financing Receivable, Modifications [Line Items]
Number of Loans and Leases | loan		0	0	0	1
Post-Modification Recorded Investment | $	[1]	$ 0	$ 0	$ 0	$ 4

[1] ost-modification balances approximate pre-modification balances. The aggregate amount of charge-offs as a result of the restructurings was not significant.

[2] ther includes covenant modifications, forbearance, loans discharged under Chapter 7 bankruptcy, or other concessions.