Restructuring - Summary of Liabilities Recognized Related to Restructuring Plan (Detail) - 2019 Restructuring Plan [Member] $ in Millions	3 Months Ended	9 Months Ended
	Sep. 30, 2020 USD ($)	Sep. 30, 2020 USD ($)
Restructuring Cost And Reserve [Line Items]
Expenses	$ 15.5	$ 82.8
Beginning Balance		27.3
Cash payments		(58.3)
Foreign currency exchange rate changes		0.3
Ending Balance	52.1	52.1
Expense incurred since the start of the 2019 Restructuring Plan	119.1	119.1
Expense estimated to be recognized for the 2019 Restructuring Plan	375.0	375.0
Employee Termination Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Expenses	6.9	43.6
Beginning Balance		23.2
Cash payments		(37.0)
Foreign currency exchange rate changes		0.3
Ending Balance	30.1	30.1
Expense incurred since the start of the 2019 Restructuring Plan	66.8	66.8
Expense estimated to be recognized for the 2019 Restructuring Plan	210.0	210.0
Contract Termination [Member]
Restructuring Cost And Reserve [Line Items]
Expenses	1.4	10.7
Cash payments		(4.3)
Ending Balance	6.4	6.4
Expense incurred since the start of the 2019 Restructuring Plan	10.7	10.7
Expense estimated to be recognized for the 2019 Restructuring Plan	25.0	25.0
Other Restructuring [Member]
Restructuring Cost And Reserve [Line Items]
Expenses	7.2	28.5
Beginning Balance		4.1
Cash payments		(17.0)
Ending Balance	15.6	15.6
Expense incurred since the start of the 2019 Restructuring Plan	41.6	41.6
Expense estimated to be recognized for the 2019 Restructuring Plan	$ 140.0	$ 140.0