Restructuring Costs (Details)	9 Months Ended
	Sep. 30, 2017 USD ($)
Restructuring Cost [Abstract]
Net restructuring costs	$ 34,500,000
Restructuring reserve [Roll Forward]
Balance, beginning of period	4,500,000
Severance Costs	24,700,000
Office closure costs and other	9,800,000
Costs paid or utilized	(17,600,000)
Balance, end of period	21,400,000
Reportable segments | Americas
Restructuring reserve [Roll Forward]
Balance, beginning of period	400,000
Severance Costs	5,800,000
Office closure costs and other	500,000
Costs paid or utilized	(3,700,000)
Balance, end of period	3,000,000
Reportable segments | Americas | United States | Reportable subsegments
Restructuring reserve [Roll Forward]
Balance, beginning of period	400,000
Balance, end of period	2,600,000
Reportable segments | Southern Europe
Restructuring reserve [Roll Forward]
Balance, beginning of period	1,300,000
Severance Costs	0
Office closure costs and other	0
Costs paid or utilized	(400,000)
Balance, end of period	900,000
Reportable segments | Southern Europe | France | Reportable subsegments
Restructuring reserve [Roll Forward]
Balance, beginning of period	1,300,000
Balance, end of period	900,000
Reportable segments | Southern Europe | Italy | Reportable subsegments
Restructuring reserve [Roll Forward]
Balance, beginning of period	0
Balance, end of period	0
Reportable segments | Northern Europe
Restructuring reserve [Roll Forward]
Balance, beginning of period	2,600,000
Severance Costs	15,600,000
Office closure costs and other	8,200,000
Costs paid or utilized	(11,400,000)
Balance, end of period	15,000,000
Reportable segments | APME
Restructuring reserve [Roll Forward]
Balance, beginning of period	100,000
Severance Costs	900,000
Office closure costs and other	500,000
Costs paid or utilized	(1,100,000)
Balance, end of period	400,000
Reportable segments | Right Management
Restructuring reserve [Roll Forward]
Balance, beginning of period	100,000
Severance Costs	1,400,000
Office closure costs and other	600,000
Costs paid or utilized	(300,000)
Balance, end of period	1,800,000
Corporate
Restructuring reserve [Roll Forward]
Balance, beginning of period	0
Severance Costs	1,000,000
Office closure costs and other	0
Costs paid or utilized	(700,000)
Balance, end of period	$ 300,000