Restructuring, Impairment and Other Charges - Schedule of Changes in the Restructuring Reserve (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost And Reserve [Line Items]
Balance at the beginning	$ 23.5	$ 21.0
Restructuring Charges	29.5	28.3	$ 25.4
Foreign Exchange and Other	0.9	1.1
Cash Paid	(32.7)	(26.9)
Balance at the end	21.2	23.5	21.0
Employee terminations
Restructuring Cost And Reserve [Line Items]
Balance at the beginning	9.6	7.6
Restructuring Charges	12.9	23.5
Foreign Exchange and Other	(1.5)	0.1
Cash Paid	(16.2)	(21.6)
Balance at the end	4.8	9.6	7.6
MEPP withdrawal obligations
Restructuring Cost And Reserve [Line Items]
Balance at the beginning	11.0	11.8
Restructuring Charges	0.7	0.7
Cash Paid	(1.5)	(1.5)
Balance at the end	10.2	11.0	11.8
Lease terminations and other
Restructuring Cost And Reserve [Line Items]
Balance at the beginning	2.9	1.6
Restructuring Charges	15.9	4.1
Foreign Exchange and Other	2.4	1.0
Cash Paid	(15.0)	(3.8)
Balance at the end	$ 6.2	$ 2.9	$ 1.6