Fair Value Measurements - Schedule of Assets Measured at Fair Value on a Recurring Basis (Details) - USD ($) $ in Millions	Apr. 01, 2018	Dec. 31, 2017
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in Persol Holdings	$ 265.2	$ 228.1
Measured on Recurring Basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	4.3	4.3
Investment in Persol Holdings	265.2	228.1
Total assets at fair value	269.5	232.4
Measured on Recurring Basis | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	4.3	4.3
Investment in Persol Holdings	265.2	228.1
Total assets at fair value	269.5	232.4
Measured on Recurring Basis | Level 2
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0.0	0.0
Investment in Persol Holdings	0.0	0.0
Total assets at fair value	0.0	0.0
Measured on Recurring Basis | Level 3
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	0.0	0.0
Investment in Persol Holdings	0.0	0.0
Total assets at fair value	$ 0.0	$ 0.0