Derivative Instruments and Hedging Activities - (Losses) Gains Related to Derivative Instruments Not Designated as Hedging Instruments (Detail) (USD $) In Thousands, unless otherwise specified	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013
Non-designated hedge interest rate derivatives
Other non-interest expense	$ 44	$ (1,216)	$ (172)	$ (126)