Share Repurchase Program - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Jun. 30, 2016
Class of Stock Disclosures [Abstract]
Purchase of Treasury Stock, shares	0	0	0	180,013
Purchase of Treasury Stock, per share value				$ 18.98
Purchase of Treasury Stock				$ 3,417
Common stock shares, available for repurchase	311,056		311,056