Inventories (Details) (USD $) In Thousands, unless otherwise specified	Mar. 31, 2012	Dec. 31, 2011
Summary of Inventories
Raw materials and subassemblies	$ 42,124	$ 45,829
Work-in-process	8,648	8,294
Finished goods	31,347	29,059
Reserve for excess and obsolete inventories	(12,786)	(13,037)
Total	$ 69,333	$ 70,145