Schedule of Revenues by Major Sources (Detail) - Truck, Parts and Other - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2022	Jun. 30, 2021	Jun. 30, 2022	Jun. 30, 2021
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	$ 6,786.2	$ 5,387.6	$ 12,892.6	$ 10,801.1
Trucks
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	5,336.4	4,152.2	10,033.5	8,385.2
Trucks | Truck Sales
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	5,130.2	3,950.4	9,611.3	7,995.4
Trucks | Revenues from extended warranties, operating leases and other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	206.2	201.8	422.2	389.8
Parts Subsegment
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	1,434.7	1,211.3	2,823.6	2,372.0
Parts Subsegment | Parts
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	1,394.5	1,176.1	2,742.6	2,302.0
Parts Subsegment | Revenues from dealer services and other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	40.2	35.2	81.0	70.0
Winch Sales and Other
Entity Wide Information Revenue From External Customer [Line Items]
Total sales and revenues	$ 15.1	$ 24.1	$ 35.5	$ 43.9