Derivative Instruments and Hedging Activities - (Losses) Gains Related to Derivative Instruments Not Designated as Hedging Instruments (Detail) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014
Non-designated hedge interest rate derivatives
Other non-interest expense	$ 70	$ (43)	$ 108	$ (216)