Segment Disclosures - Segment Revenue Per Service (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Oct. 01, 2017	Jul. 02, 2017	Apr. 02, 2017	Jan. 01, 2017	Oct. 02, 2016	Jul. 03, 2016	Apr. 03, 2016	Dec. 31, 2017	Jan. 01, 2017	Jan. 03, 2016
Revenue from Services:
Revenue from services	$ 1,422.3	$ 1,328.8	$ 1,333.6	$ 1,289.7	$ 1,304.4	$ 1,247.8	$ 1,375.5	$ 1,349.1	$ 5,374.4	$ 5,276.8	$ 5,518.2	[1]
Reporting Segments | Americas Staffing
Revenue from Services:
Revenue from services									2,345.9	2,191.6	2,209.0
Reporting Segments | GTS
Revenue from Services:
Revenue from services									1,998.9	1,977.1	1,997.2
Reporting Segments | International Staffing
Revenue from Services:
Revenue from services									1,048.2	1,127.1	1,332.7
Less: Intersegment revenue
Revenue from Services:
Revenue from services									$ (18.6)	$ (19.0)	$ (20.7)

[1] Fiscal year included 53 weeks.