Goodwill and Other Intangible Assets - Changes in Carrying Value of Goodwill by Reportable Segment (Details) $ in Millions	6 Months Ended
	Jun. 30, 2024 USD ($)
Goodwill [Roll Forward]
Balance, December 31, 2023	$ 1,586.8	[1]
Currency impact	(13.6)
Balance, June 30, 2024	1,573.2	[1]
Reportable segments | Americas
Goodwill [Roll Forward]
Balance, December 31, 2023	1,050.4	[2]
Currency impact	(1.5)	[2]
Balance, June 30, 2024	1,048.9	[2]
Reportable segments | Southern Europe
Goodwill [Roll Forward]
Balance, December 31, 2023	154.7	[3]
Currency impact	(6.0)	[3]
Balance, June 30, 2024	148.7	[3]
Reportable segments | Northern Europe
Goodwill [Roll Forward]
Balance, December 31, 2023	188.0
Currency impact	(3.0)
Balance, June 30, 2024	185.0
Reportable segments | APME
Goodwill [Roll Forward]
Balance, December 31, 2023	67.7
Currency impact	(3.1)
Balance, June 30, 2024	64.6
Corporate
Goodwill [Roll Forward]
Balance, December 31, 2023	126.0	[4]
Currency impact	0.0	[4]
Balance, June 30, 2024	$ 126.0	[4]

[1] Balances were net of accumulated impairment loss of $749.3 as of both June 30, 2024 and December 31, 2023.

[2] Balances related to the United States were $1,005.8 as of both December 31, 2023 and June 30, 2024. Effective January 1, 2024, our segment reporting was realigned to include our Puerto Rico business within Other Americas. Accordingly, United States is now adjusted to exclude Puerto Rico. All previously reported results have been restated to conform to the current year presentation.

[3] Balances related to France were $75.6 and $73.4 as of December 31, 2023 and June 30, 2024, respectively. Balances related to Italy were $3.8 and $3.7 as of December 31, 2023 and June 30, 2024, respectively

[4] The majority of the Corporate balance relates to goodwill attributable to our acquisitions of Right Management ($62.1) and Jefferson Wells ($55.5). Jefferson Wells is part of the United States reporting unit. Right Management is allocated to the reporting units of the countries in which Right Management operates. For purposes of monitoring our total assets by segment, we do not allocate the Corporate balances to the respective reportable segments as this is commensurate with how we operate our business. We do, however, include these balances within the appropriate reporting units for our goodwill impairment testing.