Reconciliation of Beginning and Ending Amount of Unrecognized Tax Benefits (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Disclosure Reconciliation Of Beginning And Ending Amount Of Unrecognized Tax Benefits [Abstract]
Balance at January 1	$ 3,223	$ 2,886
Additions based on tax positions related to the current year	1	352
Reductions in prior year tax positions	(350)
Other reductions in prior year tax positions		(15)
Balance at December 31	$ 2,874	$ 3,223