Restructuring and Severance (Detail) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015
Restructuring And Related Activities [Abstract]
Restructuring and Severance Beginning Balance	$ 633	$ 1,377
Restructuring expense incurred for the period	3,088	1,266
Other cost reduction activities for the period		81
Payments and non-cash item adjustment	(3,484)	(2,091)
Restructuring and Severance Ending Balance	$ 237	$ 633