Inventories - Schedule of Inventories (Detail) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011
Inventory Disclosure [Abstract]
Raw materials	$ 7,623	$ 9,894
Work-in-process	7,886	5,606
Finished products	28,308	27,142
Field inventory	22,629	23,237
Consignment inventory	6,155	6,981
Deferred cost of sales	10,772	8,668
Inventory, net	$ 83,373	$ 81,528