Inventories (Details) (USD $) In Thousands, unless otherwise specified	Jul. 01, 2012	Dec. 31, 2011
Inventory Disclosure [Abstract]
Raw materials and assembled parts	$ 71,251	$ 68,105
Service inventories, estimated current requirements	15,593	13,978
Work-in-process	81,360	66,275
Finished goods	25,093	33,652
Total current inventories	193,297	182,010
Non-current inventories	$ 64,029	$ 57,575