Schedule of Revenues by Major Sources (Detail) - Truck, Parts and Other - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	$ 33,315.5	$ 27,314.3	$ 21,834.5
Trucks
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	26,846.4	21,486.2	16,799.7
Trucks | Truck Sales
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	25,946.4	20,644.8	15,989.7
Trucks | Revenues from extended warranties, operating leases and other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	900.0	841.4	810.0
Parts Subsegment
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	6,414.4	5,764.3	4,944.3
Parts Subsegment | Parts
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	6,223.1	5,596.8	4,809.7
Parts Subsegment | Revenues from dealer services and other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	191.3	167.5	134.6
Winch Sales and Other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	$ 54.7	$ 63.8	$ 90.5