Inventories (Details) (USD $) In Thousands, unless otherwise specified	Apr. 01, 2012	Dec. 31, 2011
Inventory Disclosure [Abstract]
Raw materials and assembled parts	$ 75,427	$ 68,105
Service inventories, estimated current requirements	15,129	13,978
Work-in-process	66,120	66,275
Finished goods	37,375	33,652
Total current inventories	194,051	182,010
Non-current inventories	$ 61,687	$ 57,575

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of merchandise or goods held by the company that are readily available for sale.

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Carrying amount (lower of cost or market) as of the balance sheet date of inventories less all valuation and other allowances. Excludes noncurrent inventory balances (expected to remain on hand past one year or one operating cycle, if longer).

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Inventories not expected to be converted to cash, sold or exchanged within the normal operating cycle.

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date for elements of machinery or equipment held for the purpose of replacing similar parts in the course of repair or maintenance.

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Carrying amount, net of valuation reserves and adjustments, as of the balance sheet date of unprocessed items to be consumed in the manufacturing or production process.

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Carrying amount, net of reserves and adjustments, as of the balance sheet date of merchandise or goods which are partially completed. This inventory is generally comprised of raw materials, labor and factory overhead costs, which require further materials, labor and overhead to be converted into finished goods, and which generally require the use of estimates to determine percentage complete and pricing.

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