Summary of Significant Accounting Policies - Schedule of Goodwill, Finite-Lived Intangible Assets and Indefinite-Lived Intangible Assets (Details) - USD ($) $ in Millions		Dec. 31, 2023		Dec. 31, 2022		Dec. 31, 2021
Goodwill [Line Items]
Goodwill	[2]	$ 1,586.8	[1]	$ 1,628.1	[1]	$ 1,722.2
Finite-lived:
Gross		846.4		840.2
Accumulated Amortization		507.2		468.3
Net		339.2		371.9
Indefinite-lived:
Gross		180.4		177.6
Total intangible assets
Gross		1,026.8		1,017.8
Accumulated Amortization		507.2		468.3
Net		519.6		549.5
Tradenames
Indefinite-lived:
Gross	[3]	52.0		52.0
Reacquired franchise rights
Indefinite-lived:
Gross		128.4		125.6
Customer relationships
Finite-lived:
Gross		824.9		818.9
Accumulated Amortization		486.0		448.1
Net		338.9		370.8
Other
Finite-lived:
Gross		21.5		21.3
Accumulated Amortization		21.2		20.2
Net		$ 0.3		$ 1.1

[1] Balances were net of accumulated impairment loss of $749.3 and $694.2 as of December 31, 2023 and 2022, respectively.

[2] Balances were net of accumulated impairment loss of $694.2 ($177.0 related to Northern Europe, $3.8 related to APME, $235.2 related to Right Management and $278.2 related to Corporate) as of December 31, 2022; and $749.3 ($232.1 related to Northern Europe, $3.8 related to APME, $235.2 related to Right Management and $278.2 related to Corporate) as of December 31, 2023.

[3] Balances were net of accumulated impairment loss of $139.5 as of both December 31, 2023 and 2022.