Common Class A [Member] Common Class B [Member] Class of Stock [Axis] Statement of Financial Position [Abstract] Cash and cash equivalents Cash and cash equivalents, beginning of period Cash and cash equivalents, end of period Accounts receivable, net Inventories, net Prepaid expenses and other Deferred income taxes, net Total current assets Investments Property and equipment, net Goodwill, net Goodwill Other assets, net Total assets Segment assets, by segment Floor plan notes payable Current maturities of long-term debt Current maturities of capital lease obligations Trade accounts payable Customer deposits Accrued expenses Total current liabilities Long-term debt, net of current maturities Capital lease obligations, net of current maturities Other long-term liabilities Deferred income taxes, net Preferred stock, par value $.01 per share; 1,000,000 shares authorized; 0 shares outstanding in 2014 and 2013 Preferred stock, par value (in Dollars per share) Preferred stock, shares authorized Preferred stock, shares outstanding Common stock, par value $.01 per share; 60,000,000 class A shares and 20,000,000 class B shares authorized; 29,850,692 class A shares and 10,075,204 class B shares outstanding in 2014; and 28,910,505 class A shares and 10,304,518 class B shares outstanding in 2013 Common stock, par value (in Dollars per share) Common stock, shares authorized Common stock, shares outstanding Additional paid-in capital Treasury stock, at cost: 2,484,498 class B shares in 2014; and 2,194,519 class B shares in 2013 Treasury stock, shares Retained earnings Accumulated other comprehensive loss, net of tax Balance, Total Balance, Total Total shareholders’ equity Total liabilities and shareholders’ equity Income Statement [Abstract] New and used truck sales Parts and service Lease and rental Finance and insurance Other Total revenue Revenues from external customers, by segment New and used truck sales Parts and service Lease and rental Total cost of products sold Gross profit Selling, general and administrative Selling, General and Administrative Expense Depreciation and amortization Gain (loss) on sale of assets Operating income Interest expense, net Income from before taxes Provision for income taxes Net income Net income Net Income Basic (in Dollars per share) Diluted (in Dollars per share) Basic (in Shares) Denominator for basic earnings per share – weighted average shares outstanding Diluted (in Shares) Denominator for diluted earnings per share – adjusted weighted average shares outstanding and assumed conversions Comprehensive income Comprehensive income Statement of Cash Flows [Abstract] Depreciation and amortization Gain on sale of property and equipment Stock-based compensation expense related to stock options and employee stock purchases Provision (benefit) for deferred income tax expense Excess tax benefits from stock-based compensation Acquired research and development Research and Development Expense Change in accounts receivable, net Change in inventories Change in prepaid expenses and other, net Change in trade accounts payable Draws on floor plan notes payable – trade, net Change in customer deposits Change in accrued expenses Net cash provided by operating activities Acquisition of property and equipment Proceeds from the sale of property and equipment Business acquisitions Proceeds from the sale of available for sale securities Change in other assets Net cash used in investing activities Draws on floor plan notes payable – non-trade, net Proceeds from long-term debt Principal payments on long-term debt Principal payments on capital lease obligations Proceeds from issuance of shares relating to employee stock options and employee stock purchases Excess tax benefits from stock-based compensation Common stock repurchased Net cash provided by financing activities Net decrease in cash and cash equivalents Interest Income taxes, net of refunds Common stock issued related to business acquistion Assets acquired under capital leases Disclosure Text Block [Abstract] Disclosure Text Block Supplement [Abstract] Commitments and Contingencies Disclosure [Abstract] Earnings Per Share [Abstract] Earnings Per Share Calculation [Abstract] Numerator for basic and diluted earnings per share – Net income available to common shareholders (in Dollars) Employee and director stock options and restricted share awards Basic earnings per common share (in Dollars per share) Diluted earnings per common share and common share equivalents (in Dollars per share) Anti-Dilutive Securities [Abstract] Anti-dilutive options Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Fair Value Disclosures [Abstract] Investment in Auction Rate Securities - Fair Value [Abstract] Major Types of Debt and Equity Securities [Axis] Auction Rate Securities [Member] Investment in auction rate securities Fair Value Available-for-sale Securities Fair Value, Hierarchy [Axis] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 3 [Member] Investment in Auction Rate Securities [Abstract] Cost Basis Amount Available-for-sale Securities, Amortized Cost Basis Gross Unrealized (Gain) Loss In Accumulated OCI Derivative Financial Instruments [Abstract] Derivative Instrument [Axis] Interest Rate Swap Agreement 1 [Member] Current Notional Amount Derivative Asset, Notional Amount Fixed Interest Rate Expiration Date Fair Value Interest Rate Swap Agreement 2 [Member] Interest Rate Swap Agreement 3 [Member] Interest Rate Swap Agreement 4 [Member] Interest Rate Swap Agreement 5 [Member] Interest Rate Swap Agreement 6 [Member] Interest Rate Swap Agreement 7 [Member] Interest Rate Swap Agreement 8 [Member] Interest Rate Swap Agreement 9 [Member] Interest Rate Swap Agreement 10 [Member] Interest Rate Swap Agreement 11 [Member] Interest Rate Swap Agreement 12 [Member] Fair Values of Derivative Instruments [Abstract] Balance Sheet Location [Axis] Other Liabilities [Member] Interest Rate Swaps Pre-tax Effect of Interest Rate Swaps [Abstract] Interest rate swaps Changes in value, Cash Flow Swaps Change in fair value of interest rate swaps Interest rate swaps Interest expense Segment Reporting [Abstract] Segment Reporting Information [Abstract] Segment income (loss) from continuing operations before taxes, by segment Segments [Axis] Truck Segment [Member] Other Segments [Member] Income Tax Disclosure [Abstract] Accmulated Other Comprehensive (Loss) [Abstract] Balance, Cash Flow Swaps Balance, Cash Flow Swaps Balance, Available for Sale Securities Balance, Available for Sale Securities Changes in value, Total Income tax deferred, Cash Flows Swaps Income tax deferred, Total Income tax expense related to components of other comprehensive income Changes in value, Available for Sale Securities Change in fair value of available-for-sale securities Sale of available for sale securities Sale of available for sale securities Income tax deferred, Available for Sale Securities Equity Components [Axis] Reclassifications [Member] Loss Reclassified From Accumulated Other Comprehensive (Loss) Into Earnings [Abstract] Income tax benefit Total reclassifications Reconciliation of Net Income to Comprehensive Income [Abstract] Unrealized gain on available-for-sale securities Other comprehensive income, before tax Other comprehensive income, net of tax Business Combinations [Abstract] Purchase Price Allocation [Abstract] Business Acquisition [Axis] CIT, Inc [Member] Property and equipment Inventory Accounts receivable Prepaid expenses Other Accrued expenses Total Assets Current assets: Liabilities and shareholders’ equity Current liabilities: Shareholders’ equity: Revenues: Cost of products sold: Earnings per common share: Weighted average shares outstanding: Cash flows from operating activities: Adjustments to reconcile net income to net cash provided by operating activities: Cash flows from investing activities: Cash flows from financing activities: Supplemental disclosure of cash flow information: Cash paid during the period for: Noncash investing activities: Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Other Assets Disclosure [Text Block] Commitments and Contingencies Disclosure [Text Block] Earnings Per Share [Text Block] Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Numerator: Denominator– Effect of dilutive securities– Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Fair Value Disclosures [Text Block] Fair Value, Assets Measured on Recurring Basis [Table Text Block] Schedule of Available-for-sale Securities Reconciliation [Table Text Block] December 31, 2013 Schedule of Derivative Instruments [Table Text Block] Schedule of Derivative Instruments in Statement of Financial Position, Fair Value [Table Text Block] Schedule of Derivative Instruments, Effect on Other Comprehensive Income (Loss) [Table Text Block] Segment Reporting Disclosure [Text Block] Schedule of Segment Reporting Information, by Segment [Table Text Block] For the nine months ended September 30, 2014 As of and for the three months ended September 30, 2013 For the nine months ended September 30, 2013 Income Tax Disclosure [Text Block] Comprehensive Income (Loss) Note [Text Block] Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Losses on cash flow swaps to: Comprehensive Income (Loss) [Table Text Block] Other comprehensive income, before tax: Business Combination Disclosure [Text Block] Schedule of Business Acquisitions, by Acquisition [Table Text Block] Finite-Lived Intangible Assets by Major Class [Axis] Computer Software, Intangible Asset [Member] Unique Name [Axis] Rush Truck Centers [Member] Concentration Risk Benchmark [Axis] Sales Revenue, Net [Member] Supplier [Axis] SAP Enterprise Software And SAP Dealership Management System [Member] Nature of Expense [Axis] Retirement Pay and Benefits [Member] Income Statement Location [Axis] Selling, General and Administrative Expenses [Member] Derivative, by Nature [Axis] Interest Rate Swap [Member] Hedging Relationship [Axis] Cash Flow Hedging [Member] Truck Parts Depot, Inc. [Member] Investment, Name [Axis] CCTTS [Member] Products and Services [Axis] CNG Fuel Systems [Member] Capitalized Computer Software, Net Capitalized Computer Software, Accumulated Amortization Finite-Lived Intangible Asset, Useful Life Number of Stores Concentration Risk, Percentage Amortization of Intangible Assets Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months Finite-Lived Intangible Assets, Amortization Expense, Year Two Finite-Lived Intangible Assets, Amortization Expense, Year Three Finite-Lived Intangible Assets, Amortization Expense, Year Five Finite-Lived Intangible Assets, Amortization Expense, Year Four Indefinite-Lived Franchise Rights Goodwill and Intangible Asset Impairment Allocated Share-based Compensation Expense Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition Available-for-sale Securities, Sold at Par Derivative, Basis Spread on Variable Rate Asset Impairment Charges Gain (Loss) on Investments, Excluding Other than Temporary Impairments Interest Rate Cash Flow Hedge Liability at Fair Value Number of Reportable Segments Number of Operating Segments Unrecognized Tax Benefits Unrecognized Tax Benefits, Interest on Income Taxes Accrued Unrecognized Tax Benefits, Income Tax Penalties Accrued Business Combination, Consideration Transferred Equity Method Investment, Ownership Percentage Payments to Acquire Equity Method Investments Business Acquisition, Equity Interest Issued or Issuable, Number of Shares (in Shares) Business Acquisition, Equity Interest Issued or Issuable, Value Assigned Class of Stock [Domain] Equity Component [Domain] Note 9 - Accumulated Other Comprehensive Income (Tables) [Table] Note 9 - Accumulated Other Comprehensive Income (Tables) [Line Items] Major Types of Debt and Equity Securities [Domain] Fair Value Hierarchy [Domain] Note 6 - Financial Instruments and Fair Value (Details) - Investment in Auction Rate Securities - Fair Value [Table] Note 6 - Financial Instruments and Fair Value (Details) - Investment in Auction Rate Securities - Fair Value [Line Items] Note 6 - Financial Instruments and Fair Value (Details) - Investment in Auction Rate Securities [Table] Note 6 - Financial Instruments and Fair Value (Details) - Investment in Auction Rate Securities [Line Items] Derivative Contract [Domain] Derivative [Table] Derivative [Line Items] Balance Sheet Location [Domain] Fair Values Derivatives, Balance Sheet Location, by Derivative Contract Type [Table] Derivatives, Fair Value [Line Items] Segments [Domain] Schedule of Segment Reporting Information, by Segment [Table] Segment Reporting Information [Line Items] Business Acquisition, Acquiree [Domain] Schedule of Business Acquisitions, by Acquisition [Table] Business Acquisition [Line Items] Share-based Goods and Nonemployee Services Transaction, Supplier [Domain] Noncash or Part Noncash Divestiture, Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Concentration Risk Benchmark [Domain] Note 2 - Other Assets (Details) [Table] Note 2 - Other Assets (Details) [Line Items] Interim Period, Costs Not Allocable [Domain] Note 3 - Commitments and Contingencies (Details) [Table] Note 3 - Commitments and Contingencies (Details) [Line Items] Income Statement Location [Domain] Note 5 - Stock Options and Restricted Stock Awards (Details) [Table] Note 5 - Stock Options and Restricted Stock Awards (Details) [Line Items] Derivative, Name [Domain] Hedging Relationship [Domain] Note 6 - Financial Instruments and Fair Value (Details) [Table] Note 6 - Financial Instruments and Fair Value (Details) [Line Items] Products and Services [Domain] Investment, Name [Domain] Note 10 - Acquisitions (Details) [Table] Note 10 - Acquisitions (Details) [Line Items] Total cost related to parts sold to retail and wholesale customers, as well as costs related to vehicle services and repairs. Revenues recognized during the period representing fees earned for the arrangement of commercial vehicle financing for customers through various institutions as well as the sale of various insurance and commercial vehicle service contracts to customers. Amounts borrowed to finance the purchase of new and used commercial vehicle inventory. Increase or decrease in amounts borrowed to finance the purchase of new and used commercial vehicle inventory. The net change during the reporting period in commercial vehicle floor plan due by the reporting entity. Represents the amount before tax, after reclassification adjustments, of appreciation (loss) in value of derivatives and unsold available-for-sale securities. Aggregate revenue recognized during the period derived from parts sold to retail and wholesale customers, as well as revenue from commercial vehicle services and repairs. CCTTS [Member] Central California Truck and Trailer Sales, LLC CIT Inc [Member] CIT, Inc. CNG Fuel Systems [Member] Compressed natural gas ("CNG") fuel systems. Interest Rate Swap Agreement 10 [Member] Interest Rate Swap Agreement 11 [Member] Interest Rate Swap Agreement 12 [Member] Interest Rate Swap Agreement 1 [Member] Interest Rate Swap Agreement 2 [Member] Interest Rate Swap Agreement 3 [Member] Interest Rate Swap Agreement 4 [Member] Interest Rate Swap Agreement 5 [Member] Interest Rate Swap Agreement 6 [Member] Interest Rate Swap Agreement 7 [Member] Interest Rate Swap Agreement 8 [Member] Interest Rate Swap Agreement 9 [Member] Reclassifications [Member] Re-classifications. Retirement Pay And Benefits [Member] Information related to retirement pay and benefits. Rush Truck Centers [Member] Rush Truck Centers. SAP Enterprise Software And SAP Dealership Management System [Member] The 2007 Long Term Incentive Plan [Member] Truck Parts Depot Inc [Member] Represents Truck Parts Depot, Inc. Truck Segment [Member] Document and Entity Information [Abstract] Document Information [Table] Document Information [Line Items] CostOfProductsSoldPartsAndServiceSales OtherComprehensiveIncomeLossOnDerivativesAndAvailableForSaleSecuritiesBeforeTax Cash and Cash Equivalents, Period Increase (Decrease) Assets, Current Capital Lease Obligations, Noncurrent Payments to Acquire Property, Plant, and Equipment Other Comprehensive Income (Loss), before Tax Liabilities, Current Other Comprehensive Income (Loss), Available-for-sale Securities, Tax Interest Income (Expense), Net Net Cash Provided by (Used in) Operating Activities Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Cost of Goods Sold Deferred Tax Assets, Net of Valuation Allowance, Current Accumulated Other Comprehensive Income (Loss), Cumulative Changes in Net Gain (Loss) from Cash Flow Hedges, Effect Net of Tax Entity Common Stock, Shares Outstanding Entity Well-known Seasoned Issuer Gain (Loss) on Disposition of Property Plant Equipment Entity Registrant Name Income (Loss) from Continuing Operations, Per Basic Share Entity Voluntary Filers Operating Income (Loss) Entity Filer Category Entity Public Float Gross Profit Document Fiscal Period Focus Current Fiscal Year End Date Earnings Per Share, Diluted Increase (Decrease) in Inventories Repayments of Long-term Capital Lease Obligations Amendment Flag Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Earnings Per Share, Basic Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax Other Comprehensive Income (Loss), Net of Tax Document Period End Date Accumulated Other Comprehensive Income (Loss), Available-for-sale Securities Adjustment, Net of Tax Net Cash Provided by (Used in) Investing Activities Cost of Revenue Operating Leases, Rent Expense Repayments of Long-term Debt Increase (Decrease) in Prepaid Expense and Other Assets Increase (Decrease) in Receivables Entity Central Index Key Other Revenue, Net Net Cash Provided by (Used in) Financing Activities Cash Flow Hedge Derivative Instrument Liabilities at Fair Value Entity Current Reporting Status Payments for Repurchase of Common Stock Excess Tax Benefit from Share-based Compensation, Operating Activities Payments for (Proceeds from) Other Investing Activities Income (Loss) from Continuing Operations Attributable to Parent Document Fiscal Year Focus Liabilities and Equity Treasury Stock, Value Payments to Acquire Businesses, Gross Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Noncontrolling Interest Business Combination, Recognized Identifiable Assets Acquired and Liabilities Assumed, Current Liabilities Amendment Description Document Type Stockholders' Equity Attributable to Parent Income Tax Expense (Benefit) Depreciation, Depletion and Amortization, Nonproduction Statement [Table] Statement [Line Items] Scenario [Axis]