Inventories - Additional Information (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Inventory Disclosure [Abstract]
Amounts credited to the allowance for obsolete inventory	$ (1.2)	$ (0.7)	$ (0.6)
Items charged to the allowance for inventory write-offs	$ 0.2	$ 0.2	$ 0.5