Inventories (Detail) (USD $) In Thousands, unless otherwise specified	Jun. 30, 2012	Dec. 31, 2011
Schedule of Inventory [Line Items]
Raw materials	$ 32,152	$ 28,675
Finished goods	8,472	7,251
Sales demonstration inventory	16,504	16,794
Reserve for excess and obsolete	(3,071)	(2,786)
Inventory	54,057	49,934
Service inventory	$ 18,160	$ 17,316