Restructuring - Summary of Liabilities Recognized Related to Restructuring Plan (Detail) - USD ($) $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2024	Sep. 30, 2024	Dec. 31, 2023	Dec. 31, 2021	Dec. 31, 2019
2023 Restructuring Plan [Member]
Restructuring Cost And Reserve [Line Items]
Beginning Balance		$ 14.2
Expenses	$ 3.0	97.0
Cash payments		(72.5)
Foreign currency exchange rate changes		1.0
Non-cash activity		1.7
Ending Balance	41.4	41.4
Expense incurred since the start of the Restructuring Plan	109.8	109.8
Expense estimated to be recognized for the Restructuring Plan	120.0	120.0	$ 120.0
2023 Restructuring Plan [Member] | Employee Termination Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Beginning Balance		9.2
Expenses	2.1	83.2
Cash payments		(61.0)
Foreign currency exchange rate changes		0.8
Ending Balance	32.2	32.2
Expense incurred since the start of the Restructuring Plan	92.4	92.4
Expense estimated to be recognized for the Restructuring Plan	93.0	93.0
2023 Restructuring Plan [Member] | Contract Termination [Member]
Restructuring Cost And Reserve [Line Items]
Expenses	0.1	3.1
Cash payments		(1.6)
Ending Balance	1.5	1.5
Expense incurred since the start of the Restructuring Plan	3.1	3.1
Expense estimated to be recognized for the Restructuring Plan	10.0	10.0
2023 Restructuring Plan [Member] | Other Restructuring [Member]
Restructuring Cost And Reserve [Line Items]
Beginning Balance		5.0
Expenses	0.8	10.7
Cash payments		(9.9)
Foreign currency exchange rate changes		0.2
Non-cash activity		1.7
Ending Balance	7.7	7.7
Expense incurred since the start of the Restructuring Plan	14.3	14.3
Expense estimated to be recognized for the Restructuring Plan	17.0	17.0
2021 Restructuring Plan [Member]
Restructuring Cost And Reserve [Line Items]
Beginning Balance		24.7
Expenses	0.8	2.0
Cash payments		(11.8)
Ending Balance	14.9	14.9
Expense incurred since the start of the Restructuring Plan	171.1	171.1
Expense estimated to be recognized for the Restructuring Plan	173.0	173.0		$ 173.0
2021 Restructuring Plan [Member] | Employee Termination Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Beginning Balance		4.2
Expenses	0.1	(1.0)
Cash payments		(1.4)
Ending Balance	1.8	1.8
Expense incurred since the start of the Restructuring Plan	58.1	58.1
Expense estimated to be recognized for the Restructuring Plan	58.1	58.1
2021 Restructuring Plan [Member] | Contract Termination [Member]
Restructuring Cost And Reserve [Line Items]
Beginning Balance		17.6
Expenses	0.2	0.3
Cash payments		(7.5)
Ending Balance	10.4	10.4
Expense incurred since the start of the Restructuring Plan	74.1	74.1
Expense estimated to be recognized for the Restructuring Plan	74.9	74.9
2021 Restructuring Plan [Member] | Other Restructuring [Member]
Restructuring Cost And Reserve [Line Items]
Beginning Balance		2.9
Expenses	0.5	2.7
Cash payments		(2.9)
Ending Balance	2.7	2.7
Expense incurred since the start of the Restructuring Plan	38.9	38.9
Expense estimated to be recognized for the Restructuring Plan	40.0	40.0
2019 Restructuring Plan [Member]
Restructuring Cost And Reserve [Line Items]
Beginning Balance		52.3
Expenses	15.0	37.6
Cash payments		(50.7)
Foreign currency exchange rate changes		2.2
Ending Balance	41.4	41.4
Expense incurred since the start of the Restructuring Plan	357.0	357.0
Expense estimated to be recognized for the Restructuring Plan	400.0	400.0			$ 400.0
2019 Restructuring Plan [Member] | Employee Termination Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Beginning Balance		43.8
Expenses	4.6	20.8
Cash payments		(30.6)
Foreign currency exchange rate changes		2.2
Ending Balance	36.2	36.2
Expense incurred since the start of the Restructuring Plan	146.5	146.5
Expense estimated to be recognized for the Restructuring Plan	157.0	157.0
2019 Restructuring Plan [Member] | Contract Termination [Member]
Restructuring Cost And Reserve [Line Items]
Beginning Balance		5.6
Cash payments		(1.5)
Ending Balance	4.1	4.1
Expense incurred since the start of the Restructuring Plan	35.0	35.0
Expense estimated to be recognized for the Restructuring Plan	35.0	35.0
2019 Restructuring Plan [Member] | Other Restructuring [Member]
Restructuring Cost And Reserve [Line Items]
Beginning Balance		2.9
Expenses	10.4	16.8
Cash payments		(18.6)
Ending Balance	1.1	1.1
Expense incurred since the start of the Restructuring Plan	175.5	175.5
Expense estimated to be recognized for the Restructuring Plan	$ 208.0	$ 208.0