Reserve for Unfunded Commitments - Summary of Activity in Reserve for Unfunded Commitments (Detail) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014
Commitments and Contingencies Disclosure [Abstract]
Balance at beginning of period	$ 2,125	$ 2,045	$ 2,145	$ 2,415
Provision for losses - unfunded commitments	(40)	175	(60)	(195)
Balance at end of period	$ 2,085	$ 2,220	$ 2,085	$ 2,220