Note 11 - Share Based Compensation and Employee Benefit Plans (Details Textual) - USD ($)		12 Months Ended
	May 17, 2016	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	May 20, 2014	May 18, 2010	May 16, 2006
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		493,088
Allocated Share-based Compensation Expense		$ 12,900,000	$ 12,400,000	$ 11,300,000
Proceeds from Stock Options Exercised		6,500,000	4,300,000	12,500,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Intrinsic Value		4,800,000	2,600,000	18,700,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested in Period, Fair Value		$ 5,600,000	$ 5,100,000	$ 3,300,000
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 6.54	$ 11.27	$ 15.86
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value		$ 17.57	$ 24.75	$ 26.81
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized		$ 13,300,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition		2 years 73 days
Deferred Compensation Plan [Member]
Deferred Compensation Arrangement with Individual, Vested Percentage		100.00%
Deferred Compensation Liability, Current		$ 7,200,000	$ 4,900,000
Cash Surrender Value of Life Insurance		$ 6,800,000	4,800,000
Rush 401 Plan [Member]
Contribution Plan Period for Eligibility		90 days
Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay		10.00%
Defined Contribution Plan, Cost Recognized		$ 6,500,000	$ 6,200,000	$ 5,200,000
Rush 401 Plan [Member] | Highly Compensated Employees [Member]
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent		15.00%
Rush 401 Plan [Member] | Employees with Less than Five Years of Service [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match		20.00%
Rush 401 Plan [Member] | Employees with More Than Five Years of Service [Member]
Defined Contribution Plan, Employer Matching Contribution, Percent of Match		40.00%
Rush 401 Plan [Member] | Minimum [Member]
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent		1.00%
Rush 401 Plan [Member] | Maximum [Member]
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Percent		50.00%
Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Fair Value		$ 5,700,000
Common Class A [Member]
Share Price		$ 31.90
Employee Stock Purchase Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Purchase Price of Common Stock, Percent		85.00%
Maximum Fair Value for Employee Stock Purchase Per Year		$ 25,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Additional Shares Authorized	500,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		528,000
Common Stock, Capital Shares Reserved for Future Issuance		1,400,000
Stock Issued During Period, Shares, Employee Stock Purchase Plans		137,360	85,263
Number of Employees Eligible to Participate in Stock Purchase Plan		6,180
Number of Employees Participating in Stock Purchase Plan		1,011
The 2006 Non-Employee Director Stock Option Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized							1,500,000
Reduction in Number of Shares Reserved for Issuance						1,000,000
Number of Shares Available for Purchase With Options by Nonemployee Director Each Year		20,000
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		10 years
The 2006 Non-Employee Director Stock Option Plan [Member] | Common Class A [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		165,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized		500,000
Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures		27,038	26,460
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		493,088	485,838
The 2006 Non-Employee Director Stock Option Plan [Member] | Shares Issued to Four Non-employee Directors [Member]
Issuance of Cash for Non-employee Director Compensation, Percent		40.00%
Issuance of Stock and Cash for Non-employee Director Compensation		$ 125,000
The 2006 Non-Employee Director Stock Option Plan [Member] | Shares Issued to Three Non-employee Directors [Member] | Common Class A [Member]
Share-based Goods and Nonemployee Services Transaction, Quantity of Securities Issued			4,725
The 2006 Non-Employee Director Stock Option Plan [Member] | Shares Issued to One Nonemployee Director [Member] | Common Class A [Member]
Share-based Goods and Nonemployee Services Transaction, Quantity of Securities Issued			3,780
Payment to Nonemployee Directors			$ 25,000
The 2006 Non-Employee Director Stock Option Plan [Member] | Shares Issued to Three Non-employee Directors 2 [Member] | Common Class A [Member]
Issuance of Stock and Cash for Non-employee Director Compensation			$ 125,000
Share-based Goods and Nonemployee Services Transaction, Quantity of Securities Issued			2,835
Payment to Nonemployee Directors			$ 50,000
The 2006 Non-Employee Director Stock Option Plan [Member] | Shares Issued to Two Nonemployee Directors [Member] | Common Class A [Member]
Share-based Goods and Nonemployee Services Transaction, Quantity of Securities Issued		6,145
The 2006 Non-Employee Director Stock Option Plan [Member] | Shares Issued to Four Non-employee Directors 2 [Member] | Common Class A [Member]
Issuance of Stock and Cash for Non-employee Director Compensation		$ 125,000
Share-based Goods and Nonemployee Services Transaction, Quantity of Securities Issued		3,687
Payment to Nonemployee Directors		$ 50,000
Amended and Restated 2007 Incentive Plan [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Expiration Period		10 years
Amended and Restated 2007 Incentive Plan [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period		3 years
Amended and Restated 2007 Incentive Plan [Member] | Common Class A [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		856,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized					6,050,000
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares Per Employee		100,000
Amended and Restated 2007 Incentive Plan [Member] | Common Class B [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Available for Grant		539,000
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized					1,450,000
Share-based Compensation Arrangement by Share-based Payment Award, Maximum Number of Shares Per Employee		100,000
Amended and Restated 2007 Incentive Plan [Member] | Common Class B [Member] | Restricted Stock Units (RSUs) [Member]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Gross		268,890	259,490
Every 6 Months [Member] | Employee Stock Purchase Plan [Member]
Defined Contribution Plan, Maximum Annual Contributions Per Employee, Amount		$ 10,625