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	Mar. 31, 2014	Dec. 31, 2013
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	$ 13,433	$ 13,698
Fair value, Derivatives (included in Other Liabilities)	13,390	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)	13,433	13,698
Notional amount, Derivatives (included in Other Assets)	264,128	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)	93	85
Notional amount, Derivatives (included in Other Assets)	3,666	3,989
Other Assets [Member] | Forward Sale Contracts-Mortgage Loans [Member]
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Assets)	5	34
Notional amount, Derivatives (included in Other Assets)	3,850	5,250
Other Liabilities [Member] | Interest Rate Swap Contracts-Commercial Loans [Member]
Derivatives not Designated as Hedging Instruments
Fair value, Derivatives (included in Other Liabilities)	13,390	13,647
Notional amount, Derivatives (included in Other Liabilities)	264,128	261,754
Collateral posted, Derivatives (included in Other Liabilities)	11,157	12,611
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)	0	0
Notional amount, Derivatives (included in Other Liabilities)	$ 0	$ 0