Restructuring, Impairment and Other - Schedule of Changes in the Restructuring and MEPP Reserves (Detail) $ in Millions	9 Months Ended
	Sep. 30, 2020 USD ($)
Restructuring Cost And Reserve [Line Items]
Balance at the beginning	$ 52.5
Restructuring and Other Charges	93.9
Foreign Exchange and Other	0.8
Cash Paid	(56.1)
Balance at the end	91.1
Employee terminations
Restructuring Cost And Reserve [Line Items]
Balance at the beginning	3.5
Restructuring and Other Charges	29.9
Foreign Exchange and Other	0.0
Cash Paid	(24.0)
Balance at the end	9.4
Other
Restructuring Cost And Reserve [Line Items]
Balance at the beginning	8.5
Restructuring and Other Charges	24.8
Foreign Exchange and Other	0.8
Cash Paid	(24.6)
Balance at the end	9.5
MEPP withdrawal obligations
Restructuring Cost And Reserve [Line Items]
Balance at the beginning	40.5
Restructuring and Other Charges	39.2
Foreign Exchange and Other	0.0
Cash Paid	(7.5)
Balance at the end	$ 72.2