Fair Value Measurements (Narrative) (Details) (USD $)	3 Months Ended
	Mar. 29, 2015	Dec. 28, 2014	Mar. 30, 2014	Dec. 29, 2013	Oct. 25, 2011
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Business Combination, Contingent Consideration Arrangements, Range of Outcomes, Value, High	$ 31,400,000
Fair Value, Measurement with Unobservable Inputs Reconciliations, Recurring Basis, Liability Value	81,000	91,000	4,981,000	4,926,000
Business Combination, Contingent Consideration Arrangements, Description	Contingent consideration is measured at fair value at the acquisition date, based on the probability that revenue thresholds or product development milestones will be achieved during the earnout period, with changes in the fair value after the acquisition date affecting earnings to the extent it is to be settled in cash.
Business Combination, Contingent Consideration Arrangements, Maximum Period	3 years
Business Combination, Contingent Consideration Arrangements, Weighted Average Period	0 years 6 months
Line of Credit, Maturing January 8, 2019 [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Line of Credit Facility, Maximum Borrowing Capacity	700,000,000
Revolving credit facility outstanding balance	479,000,000	516,000,000
2021 Notes [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unsecured senior notes, face value	500,000,000				500,000,000
Long-term Debt, Gross	497,700,000	497,700,000
Debt Instrument, Unamortized Discount	2,300,000	2,300,000			3,100,000
Unsecured senior notes, fair value	548,100,000	542,700,000
Financing Lease Obligations [Member]
Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items]
Unsecured senior notes, fair value	$ 39,000,000	$ 39,300,000