Schedule of Revenues by Major Sources (Detail) - Truck, Parts and Other - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2023	Sep. 30, 2022	Sep. 30, 2023	Sep. 30, 2022
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	$ 8,232.3	$ 6,687.0	$ 24,723.7	$ 19,579.6
Trucks
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	6,636.4	5,198.2	19,877.7	15,231.7
Trucks | Truck Sales
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	6,412.4	4,991.4	19,219.7	14,602.7
Trucks | Revenues from extended warranties, operating leases and other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	224.0	206.8	658.0	629.0
Parts Subsegment
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	1,582.2	1,471.5	4,804.1	4,295.1
Parts Subsegment | Parts
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	1,533.5	1,429.3	4,660.4	4,171.9
Parts Subsegment | Revenues from dealer services and other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	48.7	42.2	143.7	123.2
Winch Sales and Other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	$ 13.7	$ 17.3	$ 41.9	$ 52.8