Revenue - Disaggregation of Revenues by Service Type (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 02, 2023	Apr. 03, 2022
Disaggregation of Revenue [Line Items]
Revenue	$ 1,268.3	$ 1,296.4
Professional & Industrial
Disaggregation of Revenue [Line Items]
Revenue	389.8	444.3
Science, Engineering & Technology
Disaggregation of Revenue [Line Items]
Revenue	306.4	317.1
Education
Disaggregation of Revenue [Line Items]
Revenue	249.4	173.4
Outsourcing & Consulting
Disaggregation of Revenue [Line Items]
Revenue	114.6	109.1
International
Disaggregation of Revenue [Line Items]
Revenue	211.8	252.8
Staffing services | Professional & Industrial
Disaggregation of Revenue [Line Items]
Revenue	271.5	334.9
Staffing services | Science, Engineering & Technology
Disaggregation of Revenue [Line Items]
Revenue	202.3	220.6
Staffing services | Education
Disaggregation of Revenue [Line Items]
Revenue	247.6	171.9
Staffing services | International
Disaggregation of Revenue [Line Items]
Revenue	205.6	241.7
Permanent placement | Professional & Industrial
Disaggregation of Revenue [Line Items]
Revenue	4.3	10.2
Permanent placement | Science, Engineering & Technology
Disaggregation of Revenue [Line Items]
Revenue	5.5	8.0
Permanent placement | Education
Disaggregation of Revenue [Line Items]
Revenue	1.8	1.5
Permanent placement | International
Disaggregation of Revenue [Line Items]
Revenue	5.9	6.9
Outcome-based services | Professional & Industrial
Disaggregation of Revenue [Line Items]
Revenue	114.0	99.2
Outcome-based services | Science, Engineering & Technology
Disaggregation of Revenue [Line Items]
Revenue	98.6	88.5
Talent solutions | Outsourcing & Consulting
Disaggregation of Revenue [Line Items]
Revenue	114.6	109.1
Talent solutions | International
Disaggregation of Revenue [Line Items]
Revenue	0.3	4.2
Total Intersegment
Disaggregation of Revenue [Line Items]
Revenue	$ (3.7)	$ (0.3)