Environmental Matters - Company's Liability for Environmental Obligations (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2024	Mar. 31, 2023	Dec. 31, 2023
Environmental Exit Cost [Line Items]
Total Balance at Beginning of Period	$ 4.6	$ 4.4
Additions	0.3	0.5
Less: Payments / Reductions	0.1	0.2
Total Balance at End of Period	4.8	4.7
Less: Current Portion	0.7	0.6	$ 0.6
Noncurrent Balance at End of Period	$ 4.1	$ 4.1	$ 4.0