Inventories (Details) (USD $) In Thousands, unless otherwise specified	Sep. 28, 2014	Dec. 31, 2013
Inventory Disclosure [Abstract]
Raw materials and assembled parts	$ 60,219	$ 61,235
Service inventories, estimated current requirements	13,208	15,197
Work-in-process	83,475	75,883
Finished goods	33,492	29,410
Total current inventories	190,394	181,725
Non-current inventories	$ 53,845	$ 62,104