Derivative Financial Instruments - Schedule of Notional Amounts and Estimated Fair Values of Interest Rate Derivative Contracts Outstanding (Detail) - USD ($) $ in Thousands	Jun. 30, 2017	Dec. 31, 2016
Designated as Hedging Instrument [Member] | Financial institution counterparties Loan/lease interest rate swaps assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	$ 40,089	$ 41,818
Estimated Fair Value	312	368
Designated as Hedging Instrument [Member] | Financial institution counterparties Loan/lease interest rate swaps liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	14,921	18,812
Estimated Fair Value	(910)	(1,278)
Non Designated as Hedging Instrument [Member] | Financial institution counterparties Loan/lease interest rate swaps assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	211,908	206,745
Estimated Fair Value	2,357	2,649
Non Designated as Hedging Instrument [Member] | Financial institution counterparties Loan/lease interest rate swaps liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	681,298	694,965
Estimated Fair Value	(23,602)	(25,466)
Non Designated as Hedging Instrument [Member] | Financial institution counterparties Loan/lease interest-rate caps assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	114,866	85,966
Estimated Fair Value	687	575
Non Designated as Hedging Instrument [Member] | Customer counterparties Loan/lease interest rate swaps assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	681,298	694,965
Estimated Fair Value	23,602	25,467
Non Designated as Hedging Instrument [Member] | Customer counterparties Loan/lease interest rate swaps liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	211,908	206,745
Estimated Fair Value	(2,357)	(2,649)
Non Designated as Hedging Instrument [Member] | Customer counterparties Loan/lease interest rate caps liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	114,866	85,966
Estimated Fair Value	$ (687)	$ (575)