Reserve for Unfunded Commitments - Summary of Activity in Reserve for Unfunded Commitments (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Commitments and Contingencies Disclosure [Abstract]
Balance at beginning of period	$ 2,475	$ 2,145	$ 2,415
Acquisitions			125
Provision for losses - Unfunded commitments	244	330	(395)
Balance at end of period	$ 2,719	$ 2,475	$ 2,145