Derivative Financial Instruments (Schedule of Notional Amounts and Estimated Fair Values of Interest Rate Derivative Contracts Outstanding) (Detail) - USD ($) $ in Thousands	Dec. 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	$ 41,818	$ 49,927
Estimated Fair Value	368	358
Designated as Hedging Instrument [Member] | Financial Institution Counterparties Loan Lease Interest Rate Swaps Liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	18,812	31,038
Estimated Fair Value	(1,278)	(2,301)
Not Designated as Hedging Instrument [Member] | Financial Institution Counterparties Loan Lease Interest Rate Swaps Assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	206,745	62,887
Estimated Fair Value	2,649	278
Not Designated as Hedging Instrument [Member] | Financial Institution Counterparties Loan Lease Interest Rate Swaps Liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	694,965	768,182
Estimated Fair Value	(25,466)	(37,522)
Not Designated as Hedging Instrument [Member] | Financial Institution Counterparties Loan Lease Interest Rate Caps Assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	85,966	74,281
Estimated Fair Value	575	682
Not Designated as Hedging Instrument [Member] | Customer Counterparties Loan Lease Interest Rate Swaps Assets [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	694,965	780,082
Estimated Fair Value	25,467	37,630
Not Designated as Hedging Instrument [Member] | Customer Counterparties Loan Lease Interest Rate Swaps Liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	206,745	50,987
Estimated Fair Value	(2,649)	(188)
Not Designated as Hedging Instrument [Member] | Customer Counterparties Loan Lease Interest Rate Caps Liabilities [Member]
Derivatives, Fair Value [Line Items]
Notional Amount	85,966	74,281
Estimated Fair Value	$ (575)	$ (682)