Fair Value Measurements - Fair Value Measurements on a Recurring Basis (Details) - USD ($) $ in Millions	Jan. 02, 2022	Jan. 03, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Investment in Persol Holdings	$ 264.3	$ 164.2
Measured on a recurring basis
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	96.3	120.3
Investment in Persol Holdings	264.3	164.2
Total assets at fair value	360.6	284.5
Brazil indemnification	(2.4)	(2.6)
Total liabilities at fair value	(7.0)	(6.4)
Measured on a recurring basis | Greenwood/Asher
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earnout, fair value	(4.6)	(2.1)
Measured on a recurring basis | Insight
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earnout, fair value	0.0	(1.7)
Measured on a recurring basis | Level 1
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Money market funds	96.3	120.3
Investment in Persol Holdings	264.3	164.2
Total assets at fair value	360.6	284.5
Brazil indemnification	0.0	0.0
Total liabilities at fair value	0.0	0.0
Measured on a recurring basis | Level 1 | Greenwood/Asher
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earnout, fair value	0.0	0.0
Measured on a recurring basis | Level 1 | Insight
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earnout, fair value	0.0	0.0
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
Investment in Persol Holdings	0.0	0.0
Total assets at fair value	0.0	0.0
Brazil indemnification	0.0	0.0
Total liabilities at fair value	0.0	0.0
Measured on a recurring basis | Level 2 | Greenwood/Asher
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earnout, fair value	0.0	0.0
Measured on a recurring basis | Level 2 | Insight
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earnout, 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
Investment in Persol Holdings	0.0	0.0
Total assets at fair value	0.0	0.0
Brazil indemnification	(2.4)	(2.6)
Total liabilities at fair value	(7.0)	(6.4)
Measured on a recurring basis | Level 3 | Greenwood/Asher
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earnout, fair value	(4.6)	(2.1)
Measured on a recurring basis | Level 3 | Insight
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Earnout, fair value	$ 0.0	$ (1.7)