Acquisitions - Schedule of Proforma Amount on Acquisition Occurred (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Business Combinations [Abstract]
Total revenues	$ 851,537	$ 892,525
Net income	$ 28,252	$ 31,799
Basic earnings per share	$ 1.10	$ 1.22
Diluted earnings per share	$ 1.10	$ 1.22