v3.26.3
Balance Sheet Classifications, Fair Value, Gross and Net Amounts of Derivative Financial Instruments (Detail) - USD ($)
$ in Millions
Sep. 30, 2026
Dec. 31, 2025
ASSETS    
Derivative assets $ 61.5 $ 63.0
Net amount $ 43.4 $ 47.0
Derivative Asset, Statement of Financial Position [Extensible Enumeration] Assets Assets
LIABILITIES    
Derivative liabilities $ 166.5 $ 166.3
Net amount $ 148.4 $ 150.3
Derivative Liability, Statement of Financial Position [Extensible Enumeration] Liabilities Liabilities
Interest-Rate Contracts | Financial Services    
ASSETS    
Less amounts not offset in financial instruments, subject to enforceable master netting arrangements $ (17.8) $ (15.6)
LIABILITIES    
Less amounts not offset in financial instruments (17.8) (15.6)
Foreign-exchange contracts | Truck, Parts and Other    
ASSETS    
Less amounts not offset in financial instruments, subject to enforceable master netting arrangements (0.2) (0.4)
LIABILITIES    
Less amounts not offset in financial instruments (0.2) (0.4)
Commodity contracts | Truck, Parts and Other    
ASSETS    
Less amounts not offset in financial instruments, subject to enforceable master netting arrangements (0.1)  
LIABILITIES    
Less amounts not offset in financial instruments (0.1)  
Designated under hedge accounting    
ASSETS    
Derivative assets 60.0 62.2
LIABILITIES    
Derivative liabilities 164.5 165.3
Designated under hedge accounting | Interest-Rate Contracts | Financial Services | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherAssets    
ASSETS    
Derivative assets 32.9 50.0
Designated under hedge accounting | Interest-Rate Contracts | Financial Services | Location, Statement of Financial Position, Balance [Axis]: pcar:DeferredTaxLiabilitiesAndOtherLiabilities    
LIABILITIES    
Derivative liabilities 142.1 76.8
Designated under hedge accounting | Foreign-exchange contracts | Financial Services | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherAssets    
ASSETS    
Derivative assets 1.8  
Designated under hedge accounting | Foreign-exchange contracts | Financial Services | Location, Statement of Financial Position, Balance [Axis]: pcar:DeferredTaxLiabilitiesAndOtherLiabilities    
LIABILITIES    
Derivative liabilities 9.6 4.2
Designated under hedge accounting | Foreign-exchange contracts | Truck, Parts and Other | Location, Statement of Financial Position, Balance [Axis]: us-gaap:AccountsPayableAndOtherAccruedLiabilitiesCurrent    
LIABILITIES    
Derivative liabilities 12.7 84.3
Designated under hedge accounting | Foreign-exchange contracts | Truck, Parts and Other | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherAssetsCurrent    
ASSETS    
Derivative assets 24.2 11.9
Designated under hedge accounting | Commodity contracts | Truck, Parts and Other | Location, Statement of Financial Position, Balance [Axis]: us-gaap:AccountsPayableAndOtherAccruedLiabilitiesCurrent    
LIABILITIES    
Derivative liabilities 0.1  
Designated under hedge accounting | Commodity contracts | Truck, Parts and Other | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherAssetsCurrent    
ASSETS    
Derivative assets 1.1 0.3
Not designated as hedging instruments    
ASSETS    
Derivative assets 1.5 0.8
LIABILITIES    
Derivative liabilities 2.0 1.0
Not designated as hedging instruments | Foreign-exchange contracts | Financial Services | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherAssets    
ASSETS    
Derivative assets   0.3
Not designated as hedging instruments | Foreign-exchange contracts | Financial Services | Location, Statement of Financial Position, Balance [Axis]: pcar:DeferredTaxLiabilitiesAndOtherLiabilities    
LIABILITIES    
Derivative liabilities 1.5 0.1
Not designated as hedging instruments | Foreign-exchange contracts | Truck, Parts and Other | Location, Statement of Financial Position, Balance [Axis]: us-gaap:AccountsPayableAndOtherAccruedLiabilitiesCurrent    
LIABILITIES    
Derivative liabilities 0.5 0.9
Not designated as hedging instruments | Foreign-exchange contracts | Truck, Parts and Other | Location, Statement of Financial Position, Balance [Axis]: us-gaap:OtherAssetsCurrent    
ASSETS    
Derivative assets $ 1.5 $ 0.5