Derivative Instruments and Hedging Activities - Notional Amounts and Fair Values of Derivatives Not Designated as Hedging Instruments (Detail) (Not designated as hedging instrument [Member], USD $) In Thousands, unless otherwise specified	Sep. 30, 2013	Dec. 31, 2012
Derivative Notional Amount And Fair Value By Balance Sheet Not Designated As Hedging Instrument [Line Items]
Notional Amount	$ 48,149	$ 108,031
Derivative Assets, Fair Value	849	1,547
Derivative Liabilities, Fair Value	361	54
Interest Rate Locks with Customers [Member]
Derivative Notional Amount And Fair Value By Balance Sheet Not Designated As Hedging Instrument [Line Items]
Notional Amount	22,340	51,768
Forward Loan Sale Commitments [Member]
Derivative Notional Amount And Fair Value By Balance Sheet Not Designated As Hedging Instrument [Line Items]
Notional Amount	25,809	56,263
Other Liabilities [Member] | Forward Loan Sale Commitments [Member]
Derivative Notional Amount And Fair Value By Balance Sheet Not Designated As Hedging Instrument [Line Items]
Derivative Liabilities, Fair Value	361	54
Other Assets [Member] | Interest Rate Locks with Customers [Member]
Derivative Notional Amount And Fair Value By Balance Sheet Not Designated As Hedging Instrument [Line Items]
Derivative Assets, Fair Value	$ 849	$ 1,547