Quarterly report pursuant to Section 13 or 15(d)

Investments (Details)

v2.4.0.8
Investments (Details) (USD $)
In Millions, unless otherwise specified
 3 Months Ended 6 Months Ended
Jun. 28, 2014
Jun. 29, 2013
Jun. 28, 2014
Jun. 29, 2013
Dec. 31, 2013
Schedule of Investments [Line Items]          
Maturity of investments, maximum     2 years    
Amortized cost $ 0.8 $ 2.7 $ 0.8 $ 2.7 $ 12.7
Gross unrealized gains 0 0 0 0 0
Gross unrealized losses 0 0 0 0 0
Fair value (net carrying amount) 0.8 2.7 0.8 2.7 12.7
Available-for-sale debt securities [Abstract]          
Due in one year or less, amortized cost 0.8 2.7 0.8 2.7 12.7
Total available-for-sale debt securities, amortized cost 0.8 2.7 0.8 2.7 12.7
Due in one year or less, fair value (net carrying amount) 0.8 2.7 0.8 2.7 12.7
Total available-for-sale debt securities, fair value (net carrying amount) 0.8 2.7 0.8 2.7 12.7
Redemptions of available-for-sale securities     11.9 107.4  
Proceeds from sale of available-for-sale securities       35.7  
Net adjustment to unrealized investment losses on available-for-sale securities 0 0 0 0  
U.S. Treasury Bills [Member]
          
Schedule of Investments [Line Items]          
Amortized cost 0.8 0.8 0.8 0.8 0.8
Gross unrealized gains 0 0 0 0 0
Gross unrealized losses 0 0 0 0 0
Fair value (net carrying amount) 0.8 0.8 0.8 0.8 0.8
Corporate Bonds [Member]
          
Schedule of Investments [Line Items]          
Amortized cost   1.9   1.9 11.9
Gross unrealized gains   0   0 0
Gross unrealized losses   0   0 0
Fair value (net carrying amount)   $ 1.9   $ 1.9 $ 11.9