Derivative and Hedging Activities - Effect of Corporation's Derivative Financial Instruments on Income Statement (Detail) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015
Interest Rate Contracts [Member] | Interest Income - Loans and Leases [Member]
Derivative [Line Items]
Derivative financial instrument, net	$ 1,368	$ 1,623
Interest Rate Contracts [Member] | Interest Expense - Short-term Borrowings [Member]
Derivative [Line Items]
Derivative financial instrument, net	286
Interest Rate Swap [Member] | Other Income [Member]
Derivative [Line Items]
Derivative financial instrument, net	(168)	(123)
Credit Risk Contracts [Member] | Other Income [Member]
Derivative [Line Items]
Derivative financial instrument, net	$ (234)	$ (105)