Stockholders' Equity - Summary of Changes in Stockholders' Equity (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
Mar. 29, 2015	Mar. 30, 2014
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Stockholders’ equity at beginning of period	$ 224.3us-gaap_StockholdersEquity	$ 295.8us-gaap_StockholdersEquity
Comprehensive loss:
Net loss	(16.3)us-gaap_NetIncomeLoss	(15.0)us-gaap_NetIncomeLoss
Foreign currency translation	(0.2)	(0.1)
Comprehensive loss	(16.5)us-gaap_ComprehensiveIncomeNetOfTax	(15.1)us-gaap_ComprehensiveIncomeNetOfTax
Exercise of stock options and warrants	0	(0.1)
Stock-based compensation	2.0	1.8
Employee stock purchase plan and restricted stock units settled in cash	1.8	1.8
Restricted stock units traded for taxes	(0.1)	(0.1)
Stockholders’ equity at end of period	$ 211.5us-gaap_StockholdersEquity	$ 284.1us-gaap_StockholdersEquity

Restricted Stock Units Traded for Taxes, Value

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- Definition

This element represents the amount of recognized equity-based compensation during the period, that is, the amount recognized as expense in the income statement (or as asset if compensation is capitalized). Alternate captions include the words "stock-based compensation".

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- Definition

Amount after tax of increase (decrease) in equity from transactions and other events and circumstances from net income and other comprehensive income, attributable to parent entity. Excludes changes in equity resulting from investments by owners and distributions to owners.

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- Definition

The portion of profit or loss for the period, net of income taxes, which is attributable to the parent.

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- Definition

Amount after tax and reclassification adjustments of gain (loss) on foreign currency translation adjustments, foreign currency transactions designated and effective as economic hedges of a net investment in a foreign entity and intra-entity foreign currency transactions that are of a long-term-investment nature.

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- Definition

Total of all stockholders' equity (deficit) items, net of receivables from officers, directors, owners, and affiliates of the entity which are attributable to the parent. The amount of the economic entity's stockholders' equity attributable to the parent excludes the amount of stockholders' equity which is allocable to that ownership interest in subsidiary equity which is not attributable to the parent (noncontrolling interest, minority interest). This excludes temporary equity and is sometimes called permanent equity.

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- Definition

Aggregate change in value for stock issued during the period as a result of employee stock purchase plan.

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Value of stock issued as a result of the exercise of stock options.

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