Note 2 - Other Assets (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended
	Dec. 31, 2013	Jun. 30, 2014	Jun. 30, 2014 SAP Enterprise Software And SAP Dealership Management System [Member] Sales Revenue, Net [Member]	Jun. 30, 2014 Rush Truck Centers [Member]	Jun. 30, 2014 Computer Software, Intangible Asset [Member]	Jun. 30, 2013 Computer Software, Intangible Asset [Member]	Jun. 30, 2014 Computer Software, Intangible Asset [Member]	Jun. 30, 2013 Computer Software, Intangible Asset [Member]
Note 2 - Other Assets (Details) [Line Items]
Capitalized Computer Software, Net		$ 39.5
Capitalized Computer Software, Accumulated Amortization		8.7
Finite-Lived Intangible Asset, Useful Life							15 years
Number of Stores				64
Concentration Risk, Percentage			68.00%
Amortization of Intangible Assets					0.8	0.7	1.6	1.5
Finite-Lived Intangible Assets, Amortization Expense, Year Two		3.3
Finite-Lived Intangible Assets, Amortization Expense, Year Three		3.3
Finite-Lived Intangible Assets, Amortization Expense, Year Four		3.3
Finite-Lived Intangible Assets, Amortization Expense, Year Five		3.3
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months		3.3
Indefinite-Lived Franchise Rights	4.5	4.5
Goodwill and Intangible Asset Impairment	$ 0