Derivative Instruments and Hedging Activities - Value of Derivative Assets and Derivative Liabilities (Detail) - Not Designated as Hedging Instruments - USD ($) $ in Thousands		Sep. 30, 2016	Dec. 31, 2015
Other Assets
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)		$ 15,255	$ 11,295
Collateral posted, Derivatives	[1]	0	0
Other Assets | Interest Rate Swaps
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)		15,255	11,295
Notional amount, Derivatives (included in Other Assets)		264,655	245,595
Collateral posted, Derivatives		0	0
Other Assets | Interest Rate Lock Commitments
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)		739	261
Notional amount, Derivatives (included in Other Assets)		21,699	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
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Liabilities)		15,202	11,276
Collateral posted, Derivatives	[1]	14,542	12,573
Other Liabilities | Interest Rate Swaps
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Liabilities)		15,202	11,276
Notional amount, Derivatives (included in Other Liabilities)		264,655	245,595
Collateral posted, Derivatives		14,542	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)		98	5
Notional amount, Derivatives (included in Other Liabilities)		$ 16,892	$ 9,800

[1] Amounts represent posted collateral.