Goodwill and Other Intangible Assets - Changes in Carrying Value of Goodwill by Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2019	Jun. 30, 2019
Goodwill [Roll Forward]
Balance, December 31, 2018		$ 1,297.1
Goodwill acquired		31.6
Currency and other impacts		(2.3)
Impairment charge	$ (64.0)	(64.0)
Balance, June 30, 2019	1,262.4	1,262.4
Reportable segments \| Americas
Goodwill [Roll Forward]
Balance, December 31, 2018		519.9
Goodwill acquired		0.4
Currency and other impacts		1.7
Balance, June 30, 2019	522.0	522.0
Reportable segments \| Southern Europe
Goodwill [Roll Forward]
Balance, December 31, 2018		112.2
Goodwill acquired		31.2
Currency and other impacts		(0.6)
Balance, June 30, 2019	142.8	142.8
Reportable segments \| Northern Europe
Goodwill [Roll Forward]
Balance, December 31, 2018		435.4
Currency and other impacts		(4.1)
Impairment charge		(60.2)
Balance, June 30, 2019	371.1	371.1
Reportable segments \| APME
Goodwill [Roll Forward]
Balance, December 31, 2018		102.0
Currency and other impacts		0.7
Impairment charge		(3.8)
Balance, June 30, 2019	98.9	98.9
Reportable segments \| Right Management
Goodwill [Roll Forward]
Balance, December 31, 2018		62.1
Balance, June 30, 2019	62.1	62.1
Corporate
Goodwill [Roll Forward]
Balance, December 31, 2018		65.5
Balance, June 30, 2019	$ 65.5	$ 65.5

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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