Fair Value Of Financial Instruments Fair Value of Short-Term Investments (Details) (USD $) In Millions, unless otherwise specified	Sep. 26, 2014	Dec. 31, 2013
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carried at Amortized Cost	$ 2.8	$ 116.2
Fair Value	2.8	116.2
Commercial paper
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carried at Amortized Cost	0	15.5
Fair Value	0	15.5
Corporate bonds
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carried at Amortized Cost	2.8	93.7
Fair Value	2.8	93.7
Government agencies
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Carried at Amortized Cost	0	7.0
Fair Value	$ 0	$ 7.0