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Fair Value Measurements - Narrative (Details) - USD ($)
$ in Millions
 12 Months Ended
Dec. 31, 2017
Jan. 01, 2017
Jan. 03, 2016
 [1]
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Unrealized gain (loss) on available-for-sale investment, net of tax $ 56.2 $ (1.1) $ 28.6
Persol Holdings Investment      
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]      
Unrealized gain (loss) on available-for-sale investment, net of tax 56.2 (1.1)  
Cost of available-for-sale investment $ 18.4 $ 17.7  
[1] Fiscal year included 53 weeks.