Fair Value Measurements - Schedule of Assets Measured at Fair Value on a Recurring Basis (Details) - Measured on Recurring Basis - USD ($) $ in Millions	Sep. 27, 2015	Dec. 28, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	$ 3.7	$ 3.3
Available-for-sale investment	133.6	97.9
Total assets at fair value	137.3	101.2
Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	3.7	3.3
Available-for-sale investment	133.6	97.9
Total assets at fair value	137.3	101.2
Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0.0	0.0
Available-for-sale investment	0.0	0.0
Total assets at fair value	0.0	0.0
Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0.0	0.0
Available-for-sale investment	0.0	0.0
Total assets at fair value	$ 0.0	$ 0.0