Schedule of Revenues by Major Sources (Detail) - Truck, Parts and Other - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2024	Jun. 30, 2023	Jun. 30, 2024	Jun. 30, 2023
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	$ 8,262.3	$ 8,441.3	$ 16,497.3	$ 16,491.4
Trucks
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	6,577.8	6,827.5	13,118.8	13,241.3
Trucks | Truck Sales
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	6,337.6	6,601.3	12,642.3	12,807.3
Trucks | Revenues from extended warranties, operating leases and other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	240.2	226.2	476.5	434.0
Parts Subsegment
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	1,664.3	1,598.9	3,340.2	3,221.9
Parts Subsegment | Parts
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	1,614.0	1,551.4	3,239.6	3,126.9
Parts Subsegment | Revenues from dealer services and other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	50.3	47.5	100.6	95.0
Winch Sales and Other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	$ 20.2	$ 14.9	$ 38.3	$ 28.2