Schedule of Revenues by Major Sources (Detail) - Truck, Parts and Other - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2024	Sep. 30, 2023	Sep. 30, 2024	Sep. 30, 2023
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	$ 7,703.8	$ 8,232.3	$ 24,201.1	$ 24,723.7
Trucks
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	6,027.0	6,636.4	19,145.8	19,877.7
Trucks | Truck Sales
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	5,781.2	6,412.4	18,423.5	19,219.7
Trucks | Revenues from extended warranties, operating leases and other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	245.8	224.0	722.3	658.0
Parts Subsegment
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	1,657.6	1,582.2	4,997.8	4,804.1
Parts Subsegment | Parts
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	1,605.0	1,533.5	4,844.6	4,660.4
Parts Subsegment | Revenues from dealer services and other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	52.6	48.7	153.2	143.7
Winch Sales and Other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	$ 19.2	$ 13.7	$ 57.5	$ 41.9