Schedule of Revenues by Major Sources (Detail) - Truck, Parts and Other - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2022	Sep. 30, 2021	Sep. 30, 2022	Sep. 30, 2021
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	$ 6,687.0	$ 4,737.7	$ 19,579.6	$ 15,538.8
Trucks
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	5,198.2	3,452.6	15,231.7	11,837.8
Trucks | Truck Sales
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	4,991.4	3,258.3	14,602.7	11,253.7
Trucks | Revenues from extended warranties, operating leases and other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	206.8	194.3	629.0	584.1
Parts Subsegment
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	1,471.5	1,260.2	4,295.1	3,632.2
Parts Subsegment | Parts
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	1,429.3	1,226.1	4,171.9	3,528.1
Parts Subsegment | Revenues from dealer services and other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	42.2	34.1	123.2	104.1
Winch Sales and Other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	$ 17.3	$ 24.9	$ 52.8	$ 68.8