Schedule of Revenues by Major Sources (Detail) - Truck, Parts and Other - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2023	Jun. 30, 2022	Jun. 30, 2023	Jun. 30, 2022
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	$ 8,441.3	$ 6,786.2	$ 16,491.4	$ 12,892.6
Trucks
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	6,827.5	5,336.4	13,241.3	10,033.5
Trucks | Truck Sales
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	6,601.3	5,130.2	12,807.3	9,611.3
Trucks | Revenues from extended warranties, operating leases and other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	226.2	206.2	434.0	422.2
Parts Subsegment
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	1,598.9	1,434.7	3,221.9	2,823.6
Parts Subsegment | Parts
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	1,551.4	1,394.5	3,126.9	2,742.6
Parts Subsegment | Revenues from dealer services and other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	47.5	40.2	95.0	81.0
Winch Sales and Other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	$ 14.9	$ 15.1	$ 28.2	$ 35.5