v3.6.0.2
Document And Entity Information - USD ($)
12 Months Ended
Dec. 31, 2016
Feb. 22, 2017
Jun. 30, 2016
Document Information [Line Items]      
Entity Registrant Name RUSH ENTERPRISES INC \TX\    
Entity Central Index Key 0001012019    
Trading Symbol rusha    
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    
Entity Public Float     $ 766,151,533
Document Type 10-K    
Document Period End Date Dec. 31, 2016    
Document Fiscal Year Focus 2016    
Document Fiscal Period Focus FY    
Amendment Flag false    
Common Class B [Member]      
Document Information [Line Items]      
Entity Common Stock, Shares Outstanding (in shares)   9,060,365  
Common Class A [Member]      
Document Information [Line Items]      
Entity Common Stock, Shares Outstanding (in shares)   30,355,636