Significant Accounting Policies - Additional Information (Detail)		12 Months Ended
	Dec. 06, 2022	Dec. 31, 2023 USD ($) Segment shares	Dec. 31, 2022 USD ($) shares	Dec. 31, 2021 USD ($)	Jan. 17, 2023 shares
Accounting Policies [Abstract]
Reportable segments | Segment		3
Payment to acquire commitment value		$ 744,000,000
Deferred revenue		$ 1,229,100,000	$ 904,900,000
Liquid investments maturity period		90 days
Goodwill		$ 107,400,000	104,100,000
Derivative assets		$ 21,000,000	$ 119,400,000
Dividends payable, date declared	Dec. 06, 2022
Dividends payable, date paid	Feb. 07, 2023
Common stock dividend payable	50.00%
Common stock, issued | shares		523,300,000	522,000,000		174,035,361
Fractional shares paid in cash | shares					411
Restatement effect on percentage dividend	50.00%
Retained earnings		$ 15,780,300,000	$ 13,402,400,000
ASU 2022-02
Accounting Policies [Abstract]
Change in accounting principle, accounting standards update, adopted [true false]		true
Change in accounting principle, accounting standards update adoption date		Jan. 01, 2023
Change in accounting principle, accounting standards update, immaterial effect [true false]		true
Designated under hedge accounting
Accounting Policies [Abstract]
Derivative assets		$ 20,000,000	118,400,000
Designated under hedge accounting | Interest-Rate Contracts | Other Assets
Accounting Policies [Abstract]
Derivative assets		21,000,000
Trade Receivables
Accounting Policies [Abstract]
Trade and other receivables, net		1,822,700,000	1,600,100,000
Other Receivables
Accounting Policies [Abstract]
Trade and other receivables, net		375,400,000	319,700,000
Financial Services
Accounting Policies [Abstract]
Total operating lease revenue		736,900,000	788,800,000	$ 831,600,000
Financing receivable, recorded investment, 90 days past due and still accruing		$ 0	$ 0
Months contractual terms extended		3 months	3 months
Financial Services | Designated under hedge accounting | Interest-Rate Contracts | Other Assets
Accounting Policies [Abstract]
Derivative assets		$ 17,300,000	$ 58,000,000
Financial Services | Operating Lease
Accounting Policies [Abstract]
Total operating lease revenue		$ 736,900,000	$ 788,800,000	$ 831,600,000
Operating Lease, Lease Income, Statement of Income or Comprehensive Income [Extensible Enumeration]		Investment income	Investment income	Investment income
Depreciation and other expenses		$ 551,900,000	$ 490,000,000	$ 665,700,000
Truck, Parts and Other
Accounting Policies [Abstract]
Trade and other receivables, net		$ 2,198,100,000	$ 1,919,800,000
Trade receivable days outstanding considered past due		30 days	30 days	30 days
Allowance for credit losses for Truck, Parts and Other		$ 900,000	$ 600,000
Net charge-offs		$ 0	200,000	$ 0
Engines manufactured by PACCAR
Accounting Policies [Abstract]
Warranty period		2 years
Trucks | Truck Sales
Accounting Policies [Abstract]
Total operating lease revenue		$ 69,700,000	$ 105,900,000	$ 113,800,000
Maximum
Accounting Policies [Abstract]
Warranty period		5 years
Lease and guarantee periods (in years)		5 years
Estimated useful lives of equipment		10 years
Maximum | Financial Services
Accounting Policies [Abstract]
Operating lease term		5 years
Maximum | Financial Services | Loans and Leases
Accounting Policies [Abstract]
Contractual terms of retails loans and finance leases		5 years
Maximum | Trucks | Financial Services
Accounting Policies [Abstract]
Finance leases, lease term		5 years
Minimum
Accounting Policies [Abstract]
Warranty period		1 year
Lease and guarantee periods (in years)		3 years
Estimated useful lives of equipment		3 years
Minimum | Financial Services
Accounting Policies [Abstract]
Operating lease term		3 years
Minimum | Financial Services | Loans and Leases
Accounting Policies [Abstract]
Contractual terms of retails loans and finance leases		3 years
Minimum | Trucks | Financial Services
Accounting Policies [Abstract]
Finance leases, lease term		3 years