Supplemental Cash Flow Information - Schedule Of Noncash Investing and Financing Activities (Detail) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019
Supplemental Cash Flow Elements [Abstract]
Accrued liabilities for purchases of property, plant and equipment	$ 30.5	$ 28.8
Right-of-use assets obtained in exchange for new operating lease liabilities	29.3	36.4
Right-of-use assets obtained in exchange for new finance lease liabilities	15.0	0.2
Remeasurement of operating lease right-of-use assets	$ 1.9
Acquisition of assets through swap		$ 1.1