Segment Data - Schedule of Segment Data (Details) - USD ($) $ in Millions	3 Months Ended				6 Months Ended
	Jun. 30, 2025		Jun. 30, 2024		Jun. 30, 2025		Jun. 30, 2024
Segment Reporting Information [Line Items]
Revenues from services	$ 4,519.3		$ 4,520.7	[1]	$ 8,609.6		$ 8,924.0	[2]
Cost of Services	3,755.6		3,734.8		7,147.6		7,374.4
Selling and Administrative Expenses	789.0		684.8		1,459.1		1,382.6
Corporate expenses	(55.1)		(41.7)		(96.2)		(83.4)
Goodwill, Impairment Loss	88.7	[3]	0.0		88.7	[4]	0.0
Intangible asset amortization expense	(8.3)	[5]	(8.1)	[6]	(16.4)	[7]	(16.4)	[8]
Operating profit	(25.3)		101.1		2.9		167.0
Interest and other expenses, net	(16.5)		(8.7)		(28.0)		(17.1)
(Loss) earnings before income taxes	(41.8)		92.4		(25.1)		149.9
Intersegment Eliminations [Member]
Segment Reporting Information [Line Items]
Revenues from services	(9.7)		(20.4)	[1]	(17.3)		(40.2)	[2]
Cost of Services	(7.5)		(20.4)		(14.0)		(40.2)
Selling and Administrative Expenses	(2.2)		0.0		(3.3)		0.0
Operating unit profit	0.0		0.0		0.0		0.0
United States | Americas
Segment Reporting Information [Line Items]
Revenues from services			697.0	[9]			1,377.4	[10]
Other Americas | Americas
Segment Reporting Information [Line Items]
Revenues from services			367.4	[9]			723.4	[10]
France | Southern Europe
Segment Reporting Information [Line Items]
Revenues from services			1,164.1	[9]			2,263.4	[10]
Italy | Southern Europe
Segment Reporting Information [Line Items]
Revenues from services			434.9	[9]			839.2	[10]
Other Southern Europe | Southern Europe
Segment Reporting Information [Line Items]
Revenues from services			499.0	[9]			976.7	[10]
Reportable subsegments
Segment Reporting Information [Line Items]
Revenues from services	4,519.3		4,520.7		8,609.6		8,924.0
Cost of Services	3,755.6		3,734.8		7,147.6		7,374.4
Selling and Administrative Expenses	636.9		635.0		1,257.8		1,282.8
Operating unit profit	126.8		150.9		204.2		266.8
Reportable subsegments | Americas
Segment Reporting Information [Line Items]
Revenues from services	1,060.0		1,064.4	[1]	2,116.7		2,100.8	[2]
Cost of Services	825.1		819.0		1,655.3		1,617.2
Selling and Administrative Expenses	198.8		200.3		399.8		412.4
Operating unit profit	36.1		45.1		61.6		71.2
Reportable subsegments | Southern Europe
Segment Reporting Information [Line Items]
Revenues from services	2,149.3		2,098.0	[9]	3,983.3		4,079.3	[2]
Cost of Services	1,839.0		1,790.9	[11]	3,404.9		3,478.3	[12]
Selling and Administrative Expenses	237.0		223.9	[11]	454.9		447.9	[12]
Operating unit profit	73.3		83.2	[11]	123.5		153.1	[12]
Reportable subsegments | Northern Europe
Segment Reporting Information [Line Items]
Revenues from services	794.4		837.3	[1]	1,525.2	[2]	1,707.6	[2]
Cost of Services	663.7		690.6		1,268.1		1,410.9
Selling and Administrative Expenses	139.7		149.1		284.4		299.1
Operating unit profit	(9.0)		(2.4)		(27.3)		(2.4)
Reportable subsegments | APME
Segment Reporting Information [Line Items]
Revenues from services	525.3		541.4	[1]	1,001.7		1,076.5	[2]
Cost of Services	435.3		454.7		833.3		908.2
Selling and Administrative Expenses	63.6		61.7		122.0		123.4
Operating unit profit	26.4		25.0		46.4		44.9
Reportable subsegments | Northern Europe and APME
Segment Reporting Information [Line Items]
Revenues from services	4,529.0		4,541.1	[1]	8,626.9		8,964.2	[2]
Cost of Services	3,763.1		3,755.2		7,161.6		7,414.6
Selling and Administrative Expenses	639.1		635.0		1,261.1		1,282.8
Operating unit profit	126.8		150.9		204.2		266.8
Reportable subsegments | United States | Americas
Segment Reporting Information [Line Items]
Revenues from services	674.1	[13]	697.0	[1],[14]	1,362.9	[15]	1,377.4	[2],[16]
Cost of Services	498.2	[13]	514.3	[14]	1,015.2	[15]	1,015.8	[16]
Selling and Administrative Expenses	156.2	[13]	155.3	[14]	316.7	[15]	322.2	[16]
Operating unit profit	19.7	[13]	27.4	[14]	31.0	[15]	39.4	[16]
Reportable subsegments | Other Americas | Americas
Segment Reporting Information [Line Items]
Revenues from services	385.9		367.4	[1]	753.8		723.4	[2]
Cost of Services	326.9		304.7		640.1		601.4
Selling and Administrative Expenses	42.6		45.0		83.1		90.2
Operating unit profit	16.4		17.7		30.6		31.8
Reportable subsegments | France | Southern Europe
Segment Reporting Information [Line Items]
Revenues from services	1,149.3		1,164.1	[1]	2,115.0		2,263.4	[2]
Cost of Services	983.0		996.9	[11]	1,807.9		1,935.1	[12]
Selling and Administrative Expenses	134.0		127.4	[11]	253.8		255.8	[12]
Operating unit profit	32.3		39.8	[11]	53.3		72.5	[12]
Reportable subsegments | Italy | Southern Europe
Segment Reporting Information [Line Items]
Revenues from services	475.9		434.9	[1]	873.7		839.2	[2]
Cost of Services	400.4		360.1	[11]	734.1		696.5	[12]
Selling and Administrative Expenses	43.7		40.8	[11]	83.2		81.3	[12]
Operating unit profit	31.8		34.0	[11]	56.4		61.4	[12]
Reportable subsegments | Other Southern Europe | Southern Europe
Segment Reporting Information [Line Items]
Revenues from services	524.1		499.0	[1]	994.6		976.7	[2]
Cost of Services	455.6		433.9	[11]	862.9		846.7	[12]
Selling and Administrative Expenses	59.3		55.7	[11]	117.9		110.8	[12]
Operating unit profit	$ 9.2		$ 9.4	[11]	$ 13.8		$ 19.2	[12]

[1] Effective January 1, 2025, our segment reporting was realigned to include our Morocco business within Other Southern Europe. Accordingly, France is now adjusted to exclude Morocco. All previously reported results have been recast to conform to the current year presentation.

[2] Effective January 1, 2025, our segment reporting was realigned to include our Morocco business within Other Southern Europe. Accordingly, France is now adjusted to exclude Morocco. All previously reported results have been recast to conform to the current year presentation.

[3] Impairment charges for the three months ended June 30, 2025 consist of a goodwill impairment related to our investments in Switzerland and the United Kingdom and an impairment of an indefinite lived intangible asset in our Switzerland business.

[4] Impairment charges for the six months ended June 30, 2025 consist of a goodwill impairment related to our investments in Switzerland and the United Kingdom and an impairment of an indefinite lived intangible asset in our Switzerland business.

[5] Intangible asset amortization related to acquisitions is excluded from operating costs within the reportable segments and corporate expenses and shown separately.

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

[7] Intangible asset amortization related to acquisitions is excluded from operating costs within the reportable segments and corporate expenses and shown separately.

[8] Intangible asset amortization related to acquisitions is excluded from operating costs within the reportable segments and corporate expenses and shown separately.

[9] Effective January 1, 2025, our segment reporting was realigned to include our Morocco business within Other Southern Europe. Accordingly, France is now adjusted to exclude Morocco. All previously reported results have been recast to conform to the current year presentation.

[10] Effective January 1, 2025, our segment reporting was realigned to include our Morocco business within Other Southern Europe. Accordingly, France is now adjusted to exclude Morocco. All previously reported results have been recast to conform to the current year presentation.

[11] Effective January 1, 2025, our segment reporting was realigned to include our Morocco business within Other Southern Europe. Accordingly, France is now adjusted to exclude Morocco. All previously reported results have been recast to conform to the current year presentation.

[12] Effective January 1, 2025, our segment reporting was realigned to include our Morocco business within Other Southern Europe. Accordingly, France is now adjusted to exclude Morocco. All previously reported results have been recast to conform to the current year presentation.

[13] The United States revenues above represent revenues from our company-owned branches and franchise fees received from our franchise operations, which were $2.6 for the three months ended June 30, 2025.

[14] The United States revenues above represent revenues from our company-owned branches and franchise fees received from our franchise operations, which were $3.2 for the three months ended June 30, 2024.

[15] The United States revenues above represent revenues from our company-owned branches and franchise fees received from our franchise operations, which were $4.8 for the six months ended June 30, 2025.

[16] The United States revenues above represent revenues from our company-owned branches and franchise fees received from our franchise operations, which were $5.6 for the six months ended June 30, 2024.