Segment Data - Schedule of Segment Data (Details) - USD ($) $ in Millions		3 Months Ended			12 Months Ended
		Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2022		Dec. 31, 2021	Dec. 31, 2020
Segment Reporting Information [Line Items]
Revenues from services	[1]				$ 19,827.5		$ 20,724.4	$ 18,001.0
Corporate expenses					(157.0)		(154.3)	(113.9)
Goodwill Impairment charge		$ 0.0	$ 0.0	$ 0.0	(50.0)	[2],[3]	0.0	(66.8)
Intangible asset amortization expense	[4]				(37.1)		(24.2)	(27.2)
Operating profit					581.7		585.4	187.6
Interest and other expenses, net					(24.6)		(17.3)	(39.9)
Earnings before income taxes					557.1		568.1	147.7
Depreciation and Amortization Expense					84.6		73.4	76.3
Total Assets					9,130.4		9,828.9	9,328.2
Equity Investments					95.8		114.2
Additions to Long-Lived Assets					525.6		528.4	555.0
Reportable segments
Segment Reporting Information [Line Items]
Depreciation and Amortization Expense					1.6		0.7	0.1
Corporate
Segment Reporting Information [Line Items]
Goodwill Impairment charge
Total Assets	[5]				444.1		396.6	503.2
Additions to Long-Lived Assets					9.0		14.0	6.5
Segment Reconciling Items
Segment Reporting Information [Line Items]
Depreciation and Amortization Expense	[6]				37.1		24.2	27.2
Intercompany Eliminations
Segment Reporting Information [Line Items]
Revenues from services					(80.1)		(37.7)
Americas
Segment Reporting Information [Line Items]
Revenues from services					4,935.7		4,263.7	3,792.4
Operating Unit Profit (Loss)					282.6		195.2	116.0
Depreciation and Amortization Expense					10.0		9.3	10.1
Total Assets					3,640.6		3,831.6	2,485.1
Additions to Long-Lived Assets					93.8		93.2	93.5
Americas | Reportable segments
Segment Reporting Information [Line Items]
Goodwill Impairment charge
Southern Europe
Segment Reporting Information [Line Items]
Revenues from services					8,536.3		9,346.8	7,855.2
Operating Unit Profit (Loss)					413.0		416.3	237.0
Depreciation and Amortization Expense					17.7		20.0	21.8
Total Assets					3,558.4		3,691.2	4,167.2
Additions to Long-Lived Assets					253.5		237.3	251.8
Southern Europe | Reportable segments
Segment Reporting Information [Line Items]
Goodwill Impairment charge
Northern Europe
Segment Reporting Information [Line Items]
Revenues from services					4,048.3		4,670.5
Operating Unit Profit (Loss)					42.4		67.8	(27.6)
Northern Europe | Reportable segments
Segment Reporting Information [Line Items]
Goodwill Impairment charge	[3]				(50.0)
Depreciation and Amortization Expense					10.7		10.9	8.9
Total Assets					742.9		1,095.7	1,366.7
Northern Europe | Segment Reconciling Items
Segment Reporting Information [Line Items]
Additions to Long-Lived Assets					116.5		106.6	127.1
APME
Segment Reporting Information [Line Items]
Revenues from services					2,387.3		2,481.1	2,376.7
Operating Unit Profit (Loss)					87.8		84.6	70.1
APME | Reportable segments
Segment Reporting Information [Line Items]
Goodwill Impairment charge
Depreciation and Amortization Expense					7.5		8.3	8.2
Total Assets					744.4		813.8	806.0
Additions to Long-Lived Assets					52.8		77.3	76.1
Northern Europe And APME
Segment Reporting Information [Line Items]
Revenues from services					19,907.6		20,762.1	18,001.0
Operating Unit Profit (Loss)					825.8		763.9	395.5
United States | Americas
Segment Reporting Information [Line Items]
Revenues from services					3,499.3		2,743.3
United States | Americas | Reportable segments
Segment Reporting Information [Line Items]
Depreciation and Amortization Expense					7.8		6.9	7.8
Total Assets					3,243.2		3,434.6	2,103.8
United States | Americas | Segment Reconciling Items
Segment Reporting Information [Line Items]
Additions to Long-Lived Assets					79.2		76.9	73.9
Other Americas | Americas
Segment Reporting Information [Line Items]
Revenues from services					1,436.4		1,520.4
Other Americas | Americas | Reportable segments
Segment Reporting Information [Line Items]
Depreciation and Amortization Expense					2.2		2.4	2.3
Total Assets					397.4		397.0	381.3
Other Americas | Americas | Segment Reconciling Items
Segment Reporting Information [Line Items]
Additions to Long-Lived Assets					14.6		16.3	19.6
France | Southern Europe
Segment Reporting Information [Line Items]
Revenues from services					4,785.0		5,171.3
France | Southern Europe | Reportable segments
Segment Reporting Information [Line Items]
Depreciation and Amortization Expense					10.5		12.5	14.4
Total Assets					2,281.9		2,353.3	2,778.3
Additions to Long-Lived Assets					160.7		135.0	147.8
Italy | Southern Europe
Segment Reporting Information [Line Items]
Revenues from services					1,706.9		1,795.4
Italy | Southern Europe | Reportable segments
Segment Reporting Information [Line Items]
Depreciation and Amortization Expense					2.4		2.5	2.1
Total Assets					455.3		509.7	540.4
Additions to Long-Lived Assets					32.7		33.6	36.0
Other Southern Europe | Southern Europe
Segment Reporting Information [Line Items]
Revenues from services					2,044.4		2,380.1
Earnings from Equity Investments					4.8		5.0	5.3
Other Southern Europe | Southern Europe | Reportable segments
Segment Reporting Information [Line Items]
Total Assets					821.2		828.2	848.5
Other Southern Europe | Southern Europe | Segment Reconciling Items
Segment Reporting Information [Line Items]
Additions to Long-Lived Assets					60.1		68.7	68.0
Reportable subsegments | Intercompany Eliminations
Segment Reporting Information [Line Items]
Revenues from services							37.7	0.0
Reportable subsegments | Northern Europe
Segment Reporting Information [Line Items]
Revenues from services					4,048.3		4,670.5	3,976.7
Reportable subsegments | United States | Americas
Segment Reporting Information [Line Items]
Revenues from services	[1]				3,499.3		2,743.3	2,327.2
Operating Unit Profit (Loss)					219.2		136.0	60.9
Reportable subsegments | Other Americas | Americas
Segment Reporting Information [Line Items]
Revenues from services					1,436.4		1,520.4	1,465.2
Operating Unit Profit (Loss)					63.4		59.2	55.1
Reportable subsegments | France | Southern Europe
Segment Reporting Information [Line Items]
Revenues from services					4,785.0		5,171.3	4,338.1
Operating Unit Profit (Loss)					226.7		233.5	149.0
Reportable subsegments | Italy | Southern Europe
Segment Reporting Information [Line Items]
Revenues from services					1,706.9		1,795.4	1,370.7
Operating Unit Profit (Loss)					122.9		115.3	64.2
Reportable subsegments | Other Southern Europe | Southern Europe
Segment Reporting Information [Line Items]
Revenues from services					2,044.4		2,380.1	2,146.4
Operating Unit Profit (Loss)					$ 63.4		$ 67.5	$ 23.8

[1] (a) The United States revenues above represent revenues from our company-owned branches and franchise fees received from our franchise operations, which were $12.8, $12.8 and $12.6 for 2022, 2021 and 2020, respectively.

[2] Balances were net of accumulated impairment loss of $644.2 ($127.0 related to Northern Europe, $3.8 related to APME, $235.2 related to Right Management and $278.2 related to corporate) as of both January 1, 2021 and December 31, 2021; and $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.

[3] The 2022 impairment charge of $50.0 relates to our Netherlands reporting unit, which was recorded during the fourth quarter of 2022. See Note 1 to the Consolidated Financial Statements for further information.

[4] (b) Intangible asset amortization related to acquisitions is excluded from operating costs within the reportable segments and corporate expenses, and shown separately.

[5] (a) Corporate assets include assets that were not used in the operations of any segment, the most significant of which were purchased intangibles and cash.

[6] (a) Intangible asset amortization related to acquisitions is excluded from operating costs within the reportable segments and corporate expenses, and shown separately.