Restructuring Activities - Restructuring Activities (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Restructuring Cost And Reserve [Line Items]
Restructuring charges	$ 47.8	$ 12.1	$ 2.5
Total expense	61.7	28.8	40.9
Capital expenditures	1.0	21.3	123.5
Share-based compensation expense	29.9	48.5	62.9
Continuing Operations
Restructuring Cost And Reserve [Line Items]
Other associated costs	13.9	14.3	19.8
Restructuring charges	47.8	12.1	2.5
Total expense	61.7	26.4	22.3
Share-based compensation expense	1.9
Discontinued Operations
Restructuring Cost And Reserve [Line Items]
Total expense	$ 0.0	$ 2.4	$ 18.6