Derivative Instruments and Hedging Activities - Value of Derivative Assets and Derivative Liabilities (Detail) - Not Designated as Hedging Instruments - USD ($) $ in Thousands		Mar. 31, 2016	Dec. 31, 2015
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)		$ 15,281	$ 11,295
Collateral posted, Derivatives	[1]	13,293	12,573
Fair value, Derivatives (included in Other Liabilities)		15,165	11,276
Other Assets | Interest Rate Swaps
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)		15,281	11,295
Notional amount, Derivatives (included in Other Assets)		242,708	245,595
Other Assets | Interest Rate Swap Contracts-Commercial Loans
Derivatives not Designated as Hedging Instruments
Collateral posted, Derivatives		0	0
Other Assets | Interest Rate Lock Commitments
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)		526	261
Notional amount, Derivatives (included in Other Assets)		16,641	9,894
Other Assets | Forward Sale Contracts
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)		0	0
Notional amount, Derivatives (included in Other Assets)		0	0
Other Liabilities | Interest Rate Swaps
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Liabilities)		15,165	11,276
Notional amount, Derivatives (included in Other Liabilities)		242,708	245,595
Other Liabilities | Interest Rate Swap Contracts-Commercial Loans
Derivatives not Designated as Hedging Instruments
Collateral posted, Derivatives		13,293	12,753
Other Liabilities | Interest Rate Lock Commitments
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Liabilities)		0	0
Notional amount, Derivatives (included in Other Liabilities)		0	0
Other Liabilities | Forward Sale Contracts
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Liabilities)		72	5
Notional amount, Derivatives (included in Other Liabilities)		$ 13,400	$ 9,800

[1] Amounts represent posted collateral.