Document And Entity Information - shares	6 Months Ended
	Jun. 30, 2015	Aug. 01, 2015
Common Class B [Member]
Entity Common Stock, Shares Outstanding (in shares)		10,093,305
Common Class A [Member]
Entity Common Stock, Shares Outstanding (in shares)		30,264,701
Entity Registrant Name	RUSH ENTERPRISES INC \TX\
Entity Central Index Key	0001012019
Current Fiscal Year End Date	--12-31
Entity Filer Category	Large Accelerated Filer
Entity Current Reporting Status	Yes
Entity Voluntary Filers	No
Entity Well-known Seasoned Issuer	Yes
Document Type	10-Q
Document Period End Date	Jun. 30, 2015
Document Fiscal Year Focus	2015
Document Fiscal Period Focus	Q2
Amendment Flag	false