Sales and Revenues - Additional Information (Detail) - USD ($)	3 Months Ended		12 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Entity Wide Information Revenue From External Customer [Line Items]
Term used to calculate historical weighted average return rate	7 years
Estimated value of trucks to be returned	$ 646,500,000		$ 627,900,000
Estimated sales returned liabilities	681,200,000		664,100,000
Payment to acquire commitment value	1,203,200,000
Payment to acquire commitment related to lease value	317,900,000
Estimated value of returned goods	66,400,000		62,200,000
Sales returns liabilities in estimated returns	151,700,000		142,000,000.0
Financial Services
Entity Wide Information Revenue From External Customer [Line Items]
Total operating lease income	209,400,000	$ 202,800,000
Financing receivable, recorded investment, 90 days past due and still accruing	0		$ 0
Trucks | Truck Sales
Entity Wide Information Revenue From External Customer [Line Items]
Total operating lease income	20,600,000	$ 27,000,000.0
Deferred revenue	84,900,000
Deferred revenue recognize, in 2021	36,600,000
Deferred revenue recognize, in 2022	25,200,000
Deferred revenue recognize, in 2023	12,700,000
Deferred revenue recognize, in 2024	8,400,000
Deferred revenue recognize, in 2025	$ 2,000,000.0
Minimum
Entity Wide Information Revenue From External Customer [Line Items]
Lease and guarantee periods (in years)	3 years
Minimum | Financial Services
Entity Wide Information Revenue From External Customer [Line Items]
Finance leases, lease term	3 years
Operating lease term	3 years
Maximum
Entity Wide Information Revenue From External Customer [Line Items]
Lease and guarantee periods (in years)	5 years
Warranty period	5 years
Maximum | Financial Services
Entity Wide Information Revenue From External Customer [Line Items]
Finance leases, lease term	5 years
Operating lease term	5 years