Derivative Instruments and Hedging Activities - Value of Derivative Assets and Derivative Liabilities (Detail) (Not Designated as Hedging Instruments [Member], USD $) In Thousands, unless otherwise specified	Jun. 30, 2014	Dec. 31, 2013
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	$ 14,082	$ 13,698
Fair value, Derivatives (included in Other Liabilities)	14,050	13,647
Other Assets [Member] | Interest Rate Swap Contracts-Commercial Loans [Member]
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	14,082	13,698
Notional amount, Derivatives (included in Other Assets)	245,865	261,754
Collateral posted, Derivatives (included in Other Assets)	0	0
Other Assets [Member] | Interest Rate Lock Commitments - Mortgage Loans [Member]
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	292	85
Notional amount, Derivatives (included in Other Assets)	9,594	3,989
Other Assets [Member] | Forward Sale Contracts-Mortgage Loans [Member]
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	0	34
Notional amount, Derivatives (included in Other Assets)	0	5,250
Other Liabilities [Member] | Interest Rate Swap Contracts-Commercial Loans [Member]
Derivatives not Designated as Hedging Instruments
Collateral posted, Derivatives (included in Other Assets)	11,559	12,611
Fair value, Derivatives (included in Other Liabilities)	14,050	13,647
Notional amount, Derivatives (included in Other Liabilities)	245,865	261,754
Other Liabilities [Member] | Interest Rate Lock Commitments - Mortgage Loans [Member]
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 [Member] | Forward Sale Contracts-Mortgage Loans [Member]
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Liabilities)	59	0
Notional amount, Derivatives (included in Other Liabilities)	$ 7,210	$ 0