Segment Disclosures - Segment Revenue From Service (Details) - USD ($) $ in Millions	3 Months Ended
	Apr. 01, 2018	Apr. 02, 2017
Revenue from Services
Segment revenue from services	$ 1,369.9	$ 1,289.7
Less: Intersegment revenue
Revenue from Services
Segment revenue from services	(4.9)	(4.3)
Americas Staffing | Reporting Segments
Revenue from Services
Segment revenue from services	604.3	573.1
Global Talent Solutions | Reporting Segments
Revenue from Services
Segment revenue from services	485.8	487.3
International Staffing | Reporting Segments
Revenue from Services
Segment revenue from services	$ 284.7	$ 233.6