Derivative Financial Instruments - Schedule of Notional Amounts and Estimated Fair Values of Interest Rate Derivative Contracts Outstanding (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Designated as Hedging Instrument [Member] | Financial institution counterparties Loan/lease interest rate swaps assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	$ 0	$ 49,927
Estimated Fair Value	0	358
Designated as Hedging Instrument [Member] | Financial institution counterparties Loan/lease interest rate swaps liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	78,996	31,038
Estimated Fair Value	(2,734)	(2,301)
Non Designated as Hedging Instrument [Member] | Financial institution counterparties Loan/lease interest rate swaps assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	0	62,887
Estimated Fair Value	0	278
Non Designated as Hedging Instrument [Member] | Financial institution counterparties Loan/lease interest rate swaps liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	823,861	768,182
Estimated Fair Value	(54,180)	(37,522)
Non Designated as Hedging Instrument [Member] | Financial institution counterparties Loan/lease interest-rate caps assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	74,281	74,281
Estimated Fair Value	465	682
Non Designated as Hedging Instrument [Member] | Customer counterparties Loan/lease interest rate swaps assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	823,861	780,082
Estimated Fair Value	54,181	37,630
Non Designated as Hedging Instrument [Member] | Customer counterparties Loan/lease interest rate swaps liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	0	50,987
Estimated Fair Value	0	(188)
Non Designated as Hedging Instrument [Member] | Customer counterparties Loan/lease interest rate caps liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	74,281	74,281
Estimated Fair Value	$ (465)	$ (682)