v3.7.0.1
Cash Equivalents and Investments (Contractual Maturities) (Details) - USD ($)
$ in Millions
Jun. 30, 2017
Dec. 30, 2016
Investments, Debt and Equity Securities [Abstract]    
Due in less than 1 year $ 106.2  
Due in 1 to 5 years 8.2  
Due in 5-10 years 0.0  
Due after 10 years 0.0  
Available-for-sale Debt Securities, Amortized Cost $ 114.4 $ 133.3