Note 1 - Principles of Consolidation and Basis of Presentation	3 Months Ended
Mar. 31, 2020
Notes to Financial Statements
Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]	1 – Principles of Consolidation and Basis of Presentation The interim consolidated financial statements included herein have been prepared by Rush Enterprises, Inc. and its subsidiaries (collectively referred to as the “Company”), without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). All adjustments have been made to the accompanying interim consolidated financial statements, which, in the opinion of the Company’s management, are necessary for a fair presentation of its operating results. All adjustments are of a normal recurring nature. Certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles have been condensed or omitted pursuant to such rules and regulations. It is recommended that these interim consolidated financial statements be read in conjunction with the consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. Results of operations for interim periods are not necessarily indicative of results that may be expected for any other interim periods or the full fiscal year. Adoption of New Accounting Pronouncements Accounting Standards Update ("ASU") No. 2016-13, “Financial Instruments - Credit Losses (“Topic 326”): Measurement of Credit Losses on Financial Instruments,” was issued in June 2016. Under Topic 326, existing guidance on reporting credit losses for trade and other receivables, held-to-maturity debt securities, and other instruments have been replaced with a new forward-looking "expected loss" model that has resulted in the earlier recognition of allowances for losses. Under Topic 326, the Company is required to use a current expected credit loss (“CECL”) model that immediately recognizes an estimate of credit losses that are expected to occur over the life of the financial instruments that are in the scope of the update. The CECL model uses a broader range of reasonable and supportable information in the development of credit loss estimates. The Company adopted Topic 326 during the quarter ended March 31, 2020, and the new standard did not result in a material impact on its consolidated financial statements. For a complete discussion of accounting for credit losses, see Note 13 – Accounts Receivable and Allowance for Credit Losses of the Notes to Consolidated Financial Statements. COVID-19 Risks and Uncertainties In March 2020, the World Health Organization declared the disease caused by the novel strain of coronavirus (“COVID-19”) a global pandemic, and the President of the United States declared the COVID-19 outbreak a national emergency. The Company’s nationwide network of commercial vehicle dealerships are classified as “essential businesses” and have remained operational across the Company’s dealership network. The Company is monitoring the COVID-19 pandemic, and although operations were not materially affected as of the quarter ended March 31, 2020, the Company is unable to predict the impact that the COVID-19 pandemic will have on its future business and operating results due to numerous uncertainties, including the duration and severity of the outbreak.

Note 1 - Principles of Consolidation and Basis of Presentation

3 Months Ended

Mar. 31, 2020

Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block]

1 – Principles of Consolidation and Basis of Presentation

The interim consolidated financial statements included herein have been prepared by Rush Enterprises, Inc. and its subsidiaries (collectively referred to as the “Company”), without audit, pursuant to the rules and regulations of the Securities and Exchange Commission (the “SEC”). All adjustments have been made to the accompanying interim consolidated financial statements, which, in the opinion of the Company’s management, are necessary for a fair presentation of its operating results. All adjustments are of a normal recurring nature. Certain information and footnote disclosures normally included in financial statements prepared in accordance with generally accepted accounting principles have been condensed or omitted pursuant to such rules and regulations. It is recommended that these interim consolidated financial statements be read in conjunction with the consolidated financial statements and the notes thereto included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2019. Results of operations for interim periods are not necessarily indicative of results that may be expected for any other interim periods or the full fiscal year.

Adoption of New Accounting Pronouncements

Accounting Standards Update ("ASU") No. 2016-13, “Financial Instruments - Credit Losses (“Topic 326”): Measurement of Credit Losses on Financial Instruments,” was issued in June 2016. Under Topic 326, existing guidance on reporting credit losses for trade and other receivables, held-to-maturity debt securities, and other instruments have been replaced with a new forward-looking "expected loss" model that has resulted in the earlier recognition of allowances for losses. Under Topic 326, the Company is required to use a current expected credit loss (“CECL”) model that immediately recognizes an estimate of credit losses that are expected to occur over the life of the financial instruments that are in the scope of the update. The CECL model uses a broader range of reasonable and supportable information in the development of credit loss estimates. The Company adopted Topic 326 during the quarter ended March 31, 2020, and the new standard did not result in a material impact on its consolidated financial statements. For a complete discussion of accounting for credit losses, see Note 13 – Accounts Receivable and Allowance for Credit Losses of the Notes to Consolidated Financial Statements.

COVID-19 Risks and Uncertainties

In March 2020, the World Health Organization declared the disease caused by the novel strain of coronavirus (“COVID-19”) a global pandemic, and the President of the United States declared the COVID-19 outbreak a national emergency. The Company’s nationwide network of commercial vehicle dealerships are classified as “essential businesses” and have remained operational across the Company’s dealership network. The Company is monitoring the COVID-19 pandemic, and although operations were not materially affected as of the quarter ended March 31, 2020, the Company is unable to predict the impact that the COVID-19 pandemic will have on its future business and operating results due to numerous uncertainties, including the duration and severity of the outbreak.