Shareholders' Equity - Additional Information (Detail) - USD ($) $ / shares in Units, $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Aug. 31, 2015	May 31, 2008
Stockholders Equity Note [Abstract]
Common stock shares authorized for repurchase			2,000,000	2,000,000
Shares remain authorized for repurchase	1,592,026
Common stock repurchased, Shares	0	2,407,974
Aggregate purchase price		$ 63,953
Average price per repurchased shares		$ 26.56