Consolidated Statements of Operations (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
Mar. 29, 2015	Mar. 30, 2014
Total revenue	$ 355.7us-gaap_Revenues	$ 344.1us-gaap_Revenues
Cost of sales	247.7us-gaap_CostOfGoodsSold	239.9us-gaap_CostOfGoodsSold
Gross margin	108.0us-gaap_GrossProfit	104.2us-gaap_GrossProfit
Gross margin %	30.40%fcs_GrossMarginPercentage	30.30%fcs_GrossMarginPercentage
Operating expenses:
Research and development	41.7us-gaap_ResearchAndDevelopmentExpense	41.1us-gaap_ResearchAndDevelopmentExpense
Selling, general and administrative	52.7	55.5
Amortization of acquisition-related intangibles	2.1us-gaap_AmortizationOfIntangibleAssets	4.2us-gaap_AmortizationOfIntangibleAssets
Restructuring, impairments, and other costs	4.7	6.1
Charge for litigation		4.4us-gaap_LossContingencyAccrualProvision
Goodwill impairment charge	0.6us-gaap_GoodwillImpairmentLoss
Total operating expenses	101.8us-gaap_OperatingExpenses	111.3us-gaap_OperatingExpenses
Operating income (loss)	6.2us-gaap_OperatingIncomeLoss	(7.1)us-gaap_OperatingIncomeLoss
Other expense, net	1.2us-gaap_NonoperatingIncomeExpense	1.1us-gaap_NonoperatingIncomeExpense
Income (loss) before income taxes	5.0	(8.2)
Provision for income taxes	3.9us-gaap_IncomeTaxExpenseBenefit	1.1us-gaap_IncomeTaxExpenseBenefit
Net income (loss)	$ 1.1us-gaap_NetIncomeLoss	$ (9.3)us-gaap_NetIncomeLoss
Net income (loss) per common share:
Basic	$ 0.01us-gaap_EarningsPerShareBasic	$ (0.07)us-gaap_EarningsPerShareBasic
Diluted	$ 0.01us-gaap_EarningsPerShareDiluted	$ (0.07)us-gaap_EarningsPerShareDiluted
Weighted average common shares:
Basic	117.3	125.4
Diluted	120.0	125.4

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