Note 2 - Other Assets (Details) (USD $) In Millions, unless otherwise specified			3 Months Ended		3 Months Ended
	Mar. 31, 2014	Dec. 31, 2013	Mar. 31, 2014 SAP Enterprise Software And SAP Dealership Management System [Member] Sales Revenue, Net [Member]	Mar. 31, 2014 Rush Truck Centers [Member]	Mar. 31, 2014 Computer Software, Intangible Asset [Member]	Mar. 31, 2013 Computer Software, Intangible Asset [Member]
Note 2 - Other Assets (Details) [Line Items]
Capitalized Computer Software, Net	$ 39.8
Capitalized Computer Software, Accumulated Amortization	7.9
Finite-Lived Intangible Asset, Useful Life					15 years
Number of Stores				55
Concentration Risk, Percentage			60.00%
Amortization of Intangible Assets					0.8	0.7
Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months	3.3
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
Indefinite-Lived Franchise Rights	$ 4.5	$ 4.5