Goodwill and Other Intangible Assets - Changes in Goodwill by Reportable Segment (Details) $ in Millions	6 Months Ended
	Jun. 30, 2016 USD ($)
Goodwill [Roll Forward]
Balance, January 1, 2016	$ 1,257.4
Goodwill acquired	13.7
Currency and other impacts	1.2
Balance, June 30, 2016	1,272.3
Right Management
Goodwill [Roll Forward]
Balance, January 1, 2016	62.1
Balance, June 30, 2016	62.1
Reportable segments | Americas
Goodwill [Roll Forward]
Balance, January 1, 2016	515.7
Goodwill acquired	0.0
Currency and other impacts	2.7
Balance, June 30, 2016	518.4
Reportable segments | Americas | United States | Reportable subsegments
Goodwill [Roll Forward]
Balance, January 1, 2016	476.9
Balance, June 30, 2016	476.9
Reportable segments | Southern Europe
Goodwill [Roll Forward]
Balance, January 1, 2016	97.2
Goodwill acquired	0.0
Currency and other impacts	4.8
Balance, June 30, 2016	102.0
Reportable segments | Southern Europe | France | Reportable subsegments
Goodwill [Roll Forward]
Balance, January 1, 2016	69.0
Balance, June 30, 2016	70.6
Reportable segments | Southern Europe | Italy | Reportable subsegments
Goodwill [Roll Forward]
Balance, January 1, 2016	4.5
Balance, June 30, 2016	4.6
Reportable segments | Northern Europe
Goodwill [Roll Forward]
Balance, January 1, 2016	441.9
Goodwill acquired	13.7
Currency and other impacts	(10.6)
Balance, June 30, 2016	445.0
Reportable segments | APME
Goodwill [Roll Forward]
Balance, January 1, 2016	75.6
Goodwill acquired	0.0
Currency and other impacts	4.3
Balance, June 30, 2016	79.9
Reportable segments | Right Management
Goodwill [Roll Forward]
Balance, January 1, 2016	62.1
Goodwill acquired	0.0
Currency and other impacts	0.0
Balance, June 30, 2016	62.1
Corporate
Goodwill [Roll Forward]
Balance, January 1, 2016	64.9
Goodwill acquired	0.0
Currency and other impacts	0.0
Balance, June 30, 2016	64.9
Corporate | Jefferson Wells
Goodwill [Roll Forward]
Balance, June 30, 2016	$ 55.5