Segment and Related Information - Additional Information (Detail) (Other, USD $) In Millions, unless otherwise specified	12 Months Ended
Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Other
Segment Reporting Information [Line Items]
Intercompany interest income	$ 0.7	$ 0.9	$ 0.6

Amount of intercompany interest income on cash advances.

No definition available.

Name:	pcar_IntercompanyInvestmentIncome
Namespace Prefix:	pcar_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration