Other operating expenses, net (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Other Income and Expenses [Abstract]
Acquisition and integration related expenses	$ 14.1	$ 18.6	$ 45.9	$ 128.3
Stock-based compensation expense	2.6	4.4	10.9	21.7
Restructuring charges	0.9	0.6	9.7	1.2
Other employee severance costs	2.9	4.2	11.2	23.3
Other facility closure costs	0.2	5.6	2.2	5.6
Saccharin legal settlement	0.0	0.0	0.0	62.5
Fair value adjustment for warrants	1.1	(4.2)	(6.4)	(6.8)
(Gain) loss on sale of property, plant and equipment	(0.8)	0.2	(8.3)	1.7
Other	0.4	0.8	3.9	21.3
Total other operating expenses, net	$ 21.4	$ 30.2	$ 69.1	$ 258.8