v3.26.3
Amount of Loss (Gain) from Derivative Financial Instruments Recorded in Consolidated Statements of Comprehensive Income (Detail) - USD ($)
$ in Millions
 3 Months Ended 9 Months Ended
Sep. 30, 2026
Sep. 30, 2025
Sep. 30, 2026
Sep. 30, 2025
Interest-Rate Contracts        
Derivative Instruments Gain Loss [Line Items]        
Derivatives designated as hedging instruments loss (gain) $ 6.8 $ 1.0 $ 80.6 $ 177.9
Interest-Rate Contracts | Financial Services | Location, Statement of Income, Balance [Axis]: pcar:InterestAndOtherBorrowingExpense        
Derivative Instruments Gain Loss [Line Items]        
Derivatives designated as hedging instruments loss (gain) 6.8 1.0 80.6 177.9
Interest-Rate Contracts | Financial Services | Location, Statement of Income, Balance [Axis]: pcar:InterestAndOtherBorrowingExpense | Cash Flow Hedging        
Derivative Instruments Gain Loss [Line Items]        
Derivatives designated as hedging instruments loss (gain) 6.8 0.5 80.3 176.0
Interest-Rate Contracts | Financial Services | Location, Statement of Income, Balance [Axis]: pcar:InterestAndOtherBorrowingExpense | Fair Value Hedging        
Derivative Instruments Gain Loss [Line Items]        
Derivatives designated as hedging instruments loss (gain)   0.5 0.3 1.9
Foreign-exchange contracts        
Derivative Instruments Gain Loss [Line Items]        
Derivatives designated as hedging instruments loss (gain) (9.1) (4.0) 8.6 32.9
Foreign-exchange contracts | Truck, Parts and Other        
Derivative Instruments Gain Loss [Line Items]        
Derivatives designated as hedging instruments loss (gain) (6.5) (6.4) 9.4 17.8
Foreign-exchange contracts | Truck, Parts and Other | Location, Statement of Income, Balance [Axis]: us-gaap:CostOfGoodsAndServicesSold | Not designated as hedging instruments        
Derivative Instruments Gain Loss [Line Items]        
Derivatives designated as hedging instruments loss (gain) 2.5 (1.3) 1.8 (1.7)
Foreign-exchange contracts | Truck, Parts and Other | Location, Statement of Income, Balance [Axis]: us-gaap:CostOfGoodsAndServicesSold | Cash Flow Hedging        
Derivative Instruments Gain Loss [Line Items]        
Derivatives designated as hedging instruments loss (gain) 0.3 (12.2) 2.2 (23.0)
Foreign-exchange contracts | Truck, Parts and Other | Location, Statement of Income, Balance [Axis]: us-gaap:OtherNonoperatingIncomeExpense | Not designated as hedging instruments        
Derivative Instruments Gain Loss [Line Items]        
Derivatives designated as hedging instruments loss (gain) 1.5 (1.7) 3.7 6.1
Foreign-exchange contracts | Truck, Parts and Other | Location, Statement of Income, Balance [Axis]: us-gaap:OtherNonoperatingIncomeExpense | Cash Flow Hedging        
Derivative Instruments Gain Loss [Line Items]        
Derivatives designated as hedging instruments loss (gain) (11.8) 10.8   41.0
Foreign-exchange contracts | Truck, Parts and Other | Location, Statement of Income, Balance [Axis]: us-gaap:OtherNonoperatingIncomeExpense | Net Investment Hedging        
Derivative Instruments Gain Loss [Line Items]        
Derivatives designated as hedging instruments loss (gain) (1.3) (3.1) (6.4) (9.7)
Foreign-exchange contracts | Truck, Parts and Other | Location, Statement of Income, Balance [Axis]: us-gaap:Revenues | Cash Flow Hedging        
Derivative Instruments Gain Loss [Line Items]        
Derivatives designated as hedging instruments loss (gain) 2.3 1.1 8.1 5.1
Foreign-exchange contracts | Financial Services | Location, Statement of Income, Balance [Axis]: pcar:InterestAndOtherBorrowingExpense        
Derivative Instruments Gain Loss [Line Items]        
Derivatives designated as hedging instruments loss (gain) (2.6) 2.4 (0.8) 15.1
Foreign-exchange contracts | Financial Services | Location, Statement of Income, Balance [Axis]: pcar:InterestAndOtherBorrowingExpense | Not designated as hedging instruments        
Derivative Instruments Gain Loss [Line Items]        
Derivatives designated as hedging instruments loss (gain) 0.8 (0.7) (8.2) (0.8)
Foreign-exchange contracts | Financial Services | Location, Statement of Income, Balance [Axis]: pcar:InterestAndOtherBorrowingExpense | Cash Flow Hedging        
Derivative Instruments Gain Loss [Line Items]        
Derivatives designated as hedging instruments loss (gain) $ (3.4) $ 3.1 $ 7.4 $ 15.9