Inventories - Summary of Allowance for Excess and Slow-Moving Inventory (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Inventory Disclosure [Abstract]
Beginning balance	$ 33,216	$ 30,426	$ 26,228
Charges to costs and expenses	3,951	3,554	4,651
Write-offs of inventory	(2,560)	(764)	(453)
Ending balance	$ 34,607	$ 33,216	$ 30,426