Other Income (Expense), Net - Narrative (Details) - USD ($) $ in Millions	2 Months Ended	3 Months Ended	12 Months Ended
	Feb. 15, 2022	Apr. 03, 2022	Dec. 29, 2024	Dec. 31, 2023	Jan. 01, 2023
Other Income and Expense [Line Items]
Interest income, money market deposits			$ 3.0	$ 3.0
Gain on foreign currency remeasurement			0.0	0.0	$ 5.5
Equity securities gain (loss)	$ (52.4)		3.8
Disposition, increase (decrease) in indemnification liabilities			(0.7)
Motion Recruitment Partners, LLC (MRP)
Other Income and Expense [Line Items]
Business combination, acquisition related costs			8.6
Write-off of earnout liability			$ 3.4
Kelly Services Japan, Inc.
Other Income and Expense [Line Items]
Gain on foreign currency remeasurement		$ 5.5			$ 5.5
Business Talent Group, LLC
Other Income and Expense [Line Items]
Proceeds from (investment in) equity securities, investing activities				$ 2.0