Goodwill and Other Intangible Assets - Changes in Carrying Value of Goodwill by Reportable Segment (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
Sep. 30, 2019	Sep. 30, 2019
Goodwill [Roll Forward]
Balance, December 31, 2018		$ 1,297.1
Goodwill acquired		42.9
Goodwill allocated to business units sold		(20.1)
Impairment charge	$ 0.0	(64.0)
Currency and other impacts		(24.1)
Balance, September 30, 2019	1,231.8	1,231.8
Reportable segments \| Americas
Goodwill [Roll Forward]
Balance, December 31, 2018		519.9
Goodwill acquired		9.1
Currency and other impacts		0.9
Balance, September 30, 2019	529.9	529.9
Reportable segments \| Southern Europe
Goodwill [Roll Forward]
Balance, December 31, 2018		112.2
Goodwill acquired		33.8
Currency and other impacts		(5.1)
Balance, September 30, 2019	140.9	140.9
Reportable segments \| Northern Europe
Goodwill [Roll Forward]
Balance, December 31, 2018		435.4
Impairment charge		(60.2)
Currency and other impacts		(18.9)
Balance, September 30, 2019	356.3	356.3
Reportable segments \| APME
Goodwill [Roll Forward]
Balance, December 31, 2018		102.0
Goodwill allocated to business units sold		(18.5)
Impairment charge		(3.8)
Currency and other impacts		(1.0)
Balance, September 30, 2019	78.7	78.7
Reportable segments \| Right Management
Goodwill [Roll Forward]
Balance, December 31, 2018		62.1
Balance, September 30, 2019	62.1	62.1
Corporate
Goodwill [Roll Forward]
Balance, December 31, 2018		65.5
Goodwill allocated to business units sold		(1.6)
Balance, September 30, 2019	$ 63.9	$ 63.9

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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