Inventories (Detail) - USD ($) $ in Thousands	Mar. 31, 2016	Dec. 31, 2015
Inventory [Line Items]
Raw materials	$ 28,548	$ 28,190
Finished goods	20,066	17,381
Inventories, net	48,614	45,571
Service and demonstration inventory, net	$ 34,849	$ 33,709