Investment in PersolKelly Asia Pacific (Details) - USD ($) $ in Millions		3 Months Ended				12 Months Ended
	Jul. 04, 2016	Jan. 01, 2017	Oct. 02, 2016	Jul. 03, 2016	Apr. 03, 2016	Dec. 31, 2017	Jan. 01, 2017	Jan. 03, 2016		Apr. 02, 2017
Schedule of Equity Method Investments [Line Items]
Investment in equity affiliate		$ 114.8				$ 117.4	$ 114.8
Equity in net earnings (loss) of affiliate						2.7	1.1	$ (0.7)	[1]
Gain on investment in PersolKelly Asia Pacific		0.0	$ 87.2	$ 0.0	$ 0.0	0.0	87.2	0.0	[1]
Accounts payable		455.1				537.7	455.1
Payments to acquire equity method investments						0.0	0.0	0.5	[1]
PersolKelly Asia Pacific
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage	49.00%
Proceeds from investment in PersolKelly Asia Pacific equity affiliate	$ 36.5
Investment in equity affiliate	$ 104.2
Deconsolidated goodwill			1.9
Post-close cash true-up adjustment		4.5					4.5
Equity in net earnings (loss) of affiliate						2.7	1.1
Gain on investment in PersolKelly Asia Pacific			87.2
Tax expense on gain on investment in PersolKelly Asia Pacific equity affiliate			$ 23.5
Due to PersolKelly Asia Pacific		1.1				2.3	1.1
TS Kelly Workforce Solutions
Schedule of Equity Method Investments [Line Items]
Equity method investment, ownership percentage										49.00%
Repayment of loan						0.6
Payments to acquire equity method investments								$ 0.5
PersolKelly Asia Pacific
Schedule of Equity Method Investments [Line Items]
Accounts payable		$ 3.1				$ 2.5	$ 3.1

[1] Fiscal year included 53 weeks.