Fair Value Measurements - Fair Value Measurements on a Recurring Basis (Details) - USD ($) $ in Millions	Jan. 01, 2017	Jan. 03, 2016
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Available-for-sale investment	$ 141.2	$ 142.3
Measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	4.0	3.7
Available-for-sale investment	141.2	142.3
Total assets at fair value	145.2	146.0
Measured on a recurring basis | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	4.0	3.7
Available-for-sale investment	141.2	142.3
Total assets at fair value	145.2	146.0
Measured on a recurring basis | 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
Measured on a recurring basis | 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