Other Financial Statement Information - Additional Information (Detail) - USD ($) $ in Millions		3 Months Ended		9 Months Ended		12 Months Ended
	Nov. 02, 2016	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Inventory [Line Items]
Cost of inventories for certain materials using LIFO method		$ 34.5		$ 34.5		$ 32.0
Expense (benefit) charge to earnings from LIFO inventory changes		$ 1.8	$ 0.1	3.6	$ (0.1)
Accrued estimate for losses				$ 2.2		$ 2.2
Name of plaintiff				Altalink, L.P.
Complaint filling date				November 2016
Estimated damages from defendants	$ 56.0