Basis Of Presentation Summary of Significant Accounting Policies (Policies)	3 Months Ended
	Apr. 01, 2017
Organization, Consolidation and Presentation of Financial Statements [Abstract]
Basis of Accounting, Policy	The accompanying condensed consolidated financial statements include our accounts and the accounts of our subsidiaries. All intercompany accounts and transactions have been eliminated. Our interim financial statements have been prepared in accordance with generally accepted accounting principles in the United States ("U.S. GAAP") for interim financial information and the rules and regulations of the Securities and Exchange Commission ("SEC") for interim financial statements and accounting policies, consistent, in all material respects with those applied in preparing our audited consolidated financial statements included in our Annual Report on Form 10-K for the fiscal year ended December 31, 2016, filed with the SEC on March 1, 2017, as amended. Accordingly, they do not include all of the information and footnotes required by U.S. GAAP for complete financial statements. In our opinion, all adjustments, consisting of only normal recurring adjustments considered necessary for fair presentation, have been included.
Fiscal Period, Policy	Our first fiscal quarters covered by this report ended on April 1, 2017 and April 2, 2016. All references to the quarter or the three month period refer to our first fiscal quarter. Our fiscal year ends on December 31.
Use of Estimates, Policy	USE OF ESTIMATES The preparation of the financial statements and related disclosures in conformity with U.S. GAAP require us to make estimates and judgments that affect the reported amounts of assets, liabilities, revenues and expenses, and the related disclosure of contingent assets and liabilities at the date of the consolidated financial statements. By their nature, these estimates and judgments are subject to an inherent degree of uncertainty. On an ongoing basis, management evaluates its estimates, including those related to inventories, purchase order commitments, warranty obligations, asset retirement obligations, bad debts, estimated useful lives of fixed assets and intangible assets, asset impairment, intangible asset impairment, income taxes, deferred income tax valuation allowance, stock-based compensation, and contingencies and litigation. We base our estimates on historical experience and on various other analyses and assumptions that we believe to be reasonable under the circumstances, the results of which form the basis for making judgments about the carrying values of assets and liabilities that are not readily apparent from other sources. Actual results may differ from these estimates under different assumptions or conditions.
Impact of Recently Issued Accounting Standards, Policy	IMPACT OF RECENTLY ISSUED ACCOUNTING STANDARDS In May 2014, the Financial Accounting Standards Board (“FASB”) issued a new standard to achieve a consistent application of revenue recognition within the U.S., resulting in a single revenue model to be applied by reporting companies under U.S. GAAP. Under the new model, recognition of revenue occurs when a customer obtains control of promised goods or services in an amount that reflects the consideration to which the entity expects to be entitled in exchange for those goods or services. In addition, the new standard requires that reporting companies disclose the nature, amount, timing, and uncertainty of revenue and cash flows arising from contracts with customers. On July 9, 2015, the FASB agreed to delay the effective date by one year. As currently issued and amended and in accordance with the agreed upon delay, the new standard is effective for us beginning in the first quarter of 2018. Early adoption is permitted, but not before the original effective date of the standard. The new standard is required to be applied retrospectively to each prior reporting period presented or retrospectively with the cumulative effect of initially applying it recognized at the date of initial application. While we continue to assess all potential impacts of the standard, we currently believe the most significant impact will likely relate to systems revenue. Under the new standard we are evaluating whether our systems revenue would be recognized on shipment. We are planning to adopt the standard on January 1, 2018. We plan to adopt the standard retrospectively with the cumulative effect of initially applying it recognized at the date of initial application ("modified retrospective" approach). In February 2016, the FASB issued ASU 2016-02, “Leases” (Topic 842) which supersedes Topic 840, Leases. The update requires companies to generally recognize on the balance sheet operating and financing lease liabilities and corresponding right-of-use assets. The new standard is effective for us in our first quarter of fiscal year 2020 on a modified retrospective basis and earlier adoption is permitted. We are currently evaluating the impact of our pending adoption of ASU 2016-02 on our condensed consolidated financial statements.
Revenue Recognition, Policy	Revenue Recognition We recognize revenue when persuasive evidence of an arrangement exists, delivery has occurred or services have been rendered, the arrangement consideration is fixed or determinable, and collectability is reasonably assured. We derive revenue from four sources: system sales, spare parts sales, service contracts and license fees. Provided all other criteria are met, we recognize revenues on system sales when system acceptance provisions have been met in accordance with the terms and conditions of the arrangement. In the event that terms of the sale provide for a lapsing system acceptance period, we recognize revenue upon the expiration of the lapsing acceptance period or system acceptance, whichever occurs first. In these instances, which are infrequent, revenue is recorded only if the product has met product specifications prior to shipment and management deems that no significant uncertainties as to product performance exist. Our transactions frequently include the sale of systems and services under multiple element arrangements. In transactions with multiple deliverables, revenue is recognized upon the delivery of the separate elements and when system acceptance has occurred or we are otherwise released from our system acceptance obligations. For multiple element arrangements, the total consideration for an arrangement is allocated among the separate elements in the arrangement based on a selling price hierarchy. The selling price hierarchy for a deliverable is based on (i) vendor specific objective evidence (VSOE), if available; (ii) third party evidence of selling price if VSOE is not available; or (iii) an estimated selling price, if neither VSOE nor third party evidence is available. If we have not established VSOE and cannot obtain third party evidence of selling price, we determine our estimate of the relative selling price by considering our production costs and historical margins of similar products or services. We believe this best represents the price at which we would transact a sale if the product or service were sold on a stand-alone basis. We regularly review the method used to determine our relative selling price and update any estimates accordingly. We limit the amount of revenue recognized for delivered elements to the amount that is not contingent on the future delivery of products or services or other future performance obligations. We generally recognize revenue from spare parts sales upon shipment, as our products are generally sold on terms that transfer title and risk of ownership when it leaves our site. We sell service contracts for which revenue is deferred and recognized ratably over the contract period (for time-based service contracts) or as service hours are delivered (for contracts based on a purchased quantity of hours). We recognize license revenue from transactions in which our systems are re-sold by our customers to third parties, as well as from royalty arrangements. Costs related to deferred product revenues are capitalized (deferred) and recognized at the time of revenue recognition. Deferred product revenue and costs are netted on our balance sheet, under the caption “deferred product and services income.”