Restructuring - Summary of Liabilities Recognized Related to Restructuring Plan (Detail) - 2019 Restructuring Plan [Member] $ in Millions	3 Months Ended
	Mar. 31, 2020 USD ($)
Restructuring Cost And Reserve [Line Items]
Beginning Balance	$ 27.3
Additional expense	42.7
Cash payments	(22.3)
Ending Balance	47.7
Expense incurred since the start of the 2019 Restructuring Plan	79.0
Expense estimated to be recognized for the 2019 Restructuring Plan	375.0
Employee Termination Benefits [Member]
Restructuring Cost And Reserve [Line Items]
Beginning Balance	23.2
Additional expense	30.2
Cash payments	(16.4)
Ending Balance	37.0
Expense incurred since the start of the 2019 Restructuring Plan	53.4
Expense estimated to be recognized for the 2019 Restructuring Plan	170.0
Contract Termination [Member]
Restructuring Cost And Reserve [Line Items]
Additional expense	4.9
Cash payments	(0.7)
Ending Balance	4.2
Expense incurred since the start of the 2019 Restructuring Plan	4.9
Expense estimated to be recognized for the 2019 Restructuring Plan	40.0
Other Restructuring [Member]
Restructuring Cost And Reserve [Line Items]
Beginning Balance	4.1
Additional expense	7.6
Cash payments	(5.2)
Ending Balance	6.5
Expense incurred since the start of the 2019 Restructuring Plan	20.7
Expense estimated to be recognized for the 2019 Restructuring Plan	$ 165.0