Summary of Significant Accounting Policies - Narrative (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 29, 2024	Dec. 31, 2023	Jan. 01, 2023	Feb. 14, 2022	Jan. 02, 2022
Accounting Policies [Line Items]
Advertising expense	$ 9.6	$ 7.8	$ 6.4
Property and equipment, net, held for sale		27.8
Depreciation expense	12.5	12.4	13.6
Amortization of intangible assets	51.5	40.1	37.1
Intangible assets, accumulated amortization	91.4	64.1
Intangible assets, accumulated amortization, held for sale		2.3
Accounts payable	613.8	646.1
Accrued payroll and related taxes	163.9	156.2
Disposal Group, Held-for-Sale, Not Discontinued Operations
Accounting Policies [Line Items]
Short-term hosted software		0.1
Long-term hosted software		3.4
Workers Compensation
Accounting Policies [Line Items]
Liability for claims	1.0
Cloud Computing Arrangements
Accounting Policies [Line Items]
Amortization of intangible assets	11.6	6.9	$ 4.2
Intangible assets, accumulated amortization	23.5	14.2
Prepaid Expenses and Other Current Assets | Cloud Computing Arrangements
Accounting Policies [Line Items]
Short-term hosted software	4.5	4.9
Other Noncurrent Assets | Cloud Computing Arrangements
Accounting Policies [Line Items]
Long-term hosted software	41.4	27.3
Book overdrafts
Accounting Policies [Line Items]
Accounts payable	5.1	1.2
Accrued payroll and related taxes	$ 11.4	$ 9.6
PersolKelly Pte. Ltd.
Accounting Policies [Line Items]
Equity method investment, ownership percentage				49.00%	49.00%