Other Assets - Schedule of Other Assets (Details) - USD ($) $ in Millions	Dec. 31, 2023	Jan. 01, 2023	Jan. 02, 2022
Other Assets [Line Items]
Life insurance cash surrender value	$ 230.3	$ 194.3
Intangibles, net of accumulated amortization	137.7	158.7
Noncurrent restricted cash	8.0	8.6	$ 6.6
Workers' compensation receivable	11.7	12.1
Other	15.7	15.8
Total other assets, including held-for-sale	416.5
Total other assets	411.1	403.2
Equity securities, FV-NI and without readily determinable fair value	6.4	6.4
Intangible assets, accumulated amortization	64.1	44.9
PersolKelly Pte. Ltd.
Other Assets [Line Items]
Equity securities, FV-NI and without readily determinable fair value	6.4
Disposal Group, Held-for-Sale, Not Discontinued Operations | European Staffing Operations
Other Assets [Line Items]
Total other assets	5.4
Other Assets
Other Assets [Line Items]
Intangible assets, accumulated amortization	76.6	55.5
Long Term Hosted Software, net of accumulated amortization
Other Assets [Line Items]
Intangibles, net of accumulated amortization	13.1	13.7
Long Term Hosted Software, net of accumulated amortization | Other Assets
Other Assets [Line Items]
Intangible assets, accumulated amortization	$ 14.2	$ 7.3