Derivative Instruments and Hedging Activities - Income for Derivatives Not Designated as Hedging Instruments (Detail) (Not Designated as Hedging Instrument [Member], USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Derivative Instruments, Gain (Loss) [Line Items]
Income for derivatives not designated as hedging instruments	$ (10)	$ (220)	$ 225	$ (1,005)
Net (Gain) Loss on Mortgage Banking Activities [Member] | Interest Rate Locks with Customers [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Income for derivatives not designated as hedging instruments	(109)	913	339	(698)
Net (Gain) Loss on Mortgage Banking Activities [Member] | Forward Loan Sale Commitments [Member]
Derivative Instruments, Gain (Loss) [Line Items]
Income for derivatives not designated as hedging instruments	$ (99)	$ 1,133	$ 114	$ 307