Cover [Abstract] Title of 12(b) Security Security Exchange Name Entity Interactive Data Current Entity Common Stock, Shares Outstanding Entity File Number Entity Small Business Entity Current Reporting Status Entity Filer Category Document Period End Date Entity Shell Company Entity Registrant Name Entity Incorporation, State or Country Code Amendment Flag Trading Symbol Entity Address, Postal Zip Code Current Fiscal Year End Date Document Fiscal Year Focus Document Fiscal Period Focus Entity Central Index Key Entity Tax Identification Number Entity Address, Address Line One Entity Address, City or Town Document Transition Report Entity Emerging Growth Company City Area Code Local Phone Number Document Quarterly Report Entity Address, State or Province Document Type Statement of Financial Position [Abstract] Statement [Table] Statement [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Statement [Line Items] Statement [Line Items] Amortization of right-of-use assets Assets [Abstract] ASSETS Assets Total assets Property, Plant and Equipment, Net Operating property, less accumulated depreciation and amortization of $383,458 and $344,099 Other Assets, Noncurrent Other assets Assets, Current [Abstract] Current Assets Other Assets, Current Other current assets Assets, Current Total current assets Other Receivables Other receivables, including advances to independent contractors, less allowance of $9,877 and $8,125 Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents Short-term Investments Short-term investments Receivables, Net, Current Trade accounts receivable, less allowance of $10,464 and $7,074 Goodwill Goodwill Liabilities and Equity [Abstract] LIABILITIES AND SHAREHOLDERS' EQUITY Long-term Debt and Lease Obligation Long-term debt, excluding current maturities Deferred Income Taxes and Other Liabilities, Noncurrent Deferred income taxes and other noncurrent liabilities Stockholders' Equity Attributable to Parent [Abstract] Shareholders' Equity Common Stock, Value, Issued Common stock, $0.01 par value, authorized 160,000,000 shares, issued 68,380,565 and 68,232,975 shares Treasury Stock, Value Cost of 32,455,300 and 30,539,235 shares of common stock in treasury Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive loss Additional Paid in Capital, Common Stock Additional paid-in capital Retained Earnings (Accumulated Deficit) Retained earnings Stockholders' Equity Attributable to Parent Total shareholders' equity Beginning Balance Ending Balance Liabilities and Equity Total liabilities and shareholders' equity Liabilities, Current [Abstract] Current Liabilities Bank Overdrafts Cash overdraft Accounts Payable, Current Accounts payable Dividends Payable, Current Dividends payable Liabilities, Current Total current liabilities Self Insurance Reserve, Current Insurance claims Finance Lease, Liability, Current Current maturities of long-term debt Current maturities of long-term debt Other Liabilities, Current Other current liabilities Self Insurance Reserve, Noncurrent Insurance claims Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Accumulated depreciation and amortization on operating property Allowance for Doubtful Accounts, Premiums and Other Receivables Allowance on other receivables Allowance for Doubtful Accounts Receivable, Current Allowance on trade accounts receivable Common Stock, Par or Stated Value Per Share Common stock, par value Common Stock, Shares Authorized Common stock, authorized shares Common Stock, Shares, Issued Common stock, issued shares Treasury Stock, Shares Treasury stock, shares Income Statement [Abstract] Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income Net income Net income Costs and Expenses [Abstract] Costs and expenses: Purchased Transportation Costs Purchased transportation The cost of purchased transportation and transportation-related services of third party capacity providers of various modes for the carriage of customer freight during the period. Depreciation, Depletion and Amortization, Nonproduction Depreciation and amortization Depreciation and amortization Selling, General and Administrative Expense Selling, general and administrative Other Cost and Expense, Operating Other operating costs, net of gains on asset sales/dispositions Costs and Expenses Total costs and expenses Sales Commissions and Fees Commissions to agents Operating Insurance and Claims Costs, Production Insurance and claims Income Tax Expense (Benefit) Income taxes Interest Income, Operating Investment income Revenue from Contract with Customer, Excluding Assessed Tax Revenue Common Stock, Dividends, Per Share, Declared Dividends per common share Earnings Per Share, Diluted Diluted earnings per share Income (Loss) from Continuing Operations before Income Taxes, Noncontrolling Interest Income before income taxes Interest and Debt Expense Interest and debt expense Weighted Average Number of Shares Outstanding, Diluted Average diluted shares outstanding Operating Income (Loss) Operating income Operating income Statement of Comprehensive Income [Abstract] Net Income (Loss) Attributable to Parent Net income Other Comprehensive Income (Loss), Net of Tax [Abstract] Other comprehensive (loss) income: Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Foreign currency translation (losses) gains Other Comprehensive Income (Loss), Securities, Available-for-Sale, Unrealized Holding Gain (Loss) Arising During Period, after Tax Unrealized holding losses on available-for-sale investments, net of tax benefit of $2,461, $347, $436 and $104 Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Other comprehensive loss Other comprehensive loss Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive income Other Comprehensive Income (Loss), Securities, Available-for-sale, Tax Unrealized holding losses on available-for-sale investments, net of tax benefit Statement of Cash Flows [Abstract] Net Cash Provided by (Used in) Investing Activities [Abstract] INVESTING ACTIVITIES Proceeds from Sale and Maturity of Marketable Securities Sales and maturities of investments Payments to Acquire Marketable Securities Purchases of investments Proceeds from Sale of Property, Plant, and Equipment Proceeds from sales of operating property Net Cash Provided by (Used in) Investing Activities NET CASH USED BY INVESTING ACTIVITIES Payments to Acquire Property, Plant, and Equipment Purchases of operating property Expenditures on long-lived assets Payments to Acquire Other Investments Purchase of non-marketable securities Net Cash Provided by (Used in) Financing Activities [Abstract] FINANCING ACTIVITIES Proceeds from (Repayments of) Bank Overdrafts (Decrease) increase in cash overdraft Proceeds from Stock Options Exercised Proceeds from exercises of stock options Payment for Contingent Consideration Liability, Financing Activities Payment of deferred consideration Repayments of Long-term Debt, Long-term Capital Lease Obligations, and Capital Securities Principal payments on finance lease obligations Payments of Dividends Dividends paid Payments Related to Tax Withholding for Share-based Compensation Taxes paid in lieu of shares issued related to stock-based compensation plans Net Cash Provided by (Used in) Financing Activities NET CASH USED BY FINANCING ACTIVITIES Payments of Debt Issuance Costs Payment for debt issue costs Payments for Repurchase of Common Stock Purchases of common stock Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents Cash, cash equivalents and restricted cash at beginning of period Cash and cash equivalents at end of period Cash, Cash Equivalents, Restricted Cash and Restricted Cash Equivalents, Period Increase (Decrease), Including Exchange Rate Effect Decrease in cash, cash equivalents and restricted cash Effect of Exchange Rate on Cash, Cash Equivalents, Restricted Cash, and Restricted Cash Equivalents, Including Disposal Group and Discontinued Operations Effect of exchange rate changes on cash and cash equivalents Net Cash Provided by (Used in) Operating Activities [Abstract] OPERATING ACTIVITIES Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Gain (Loss) on Disposition of Property Plant Equipment Gains on sales/disposals of operating property Increase (Decrease) in Operating Capital [Abstract] Changes in operating assets and liabilities: Increase (Decrease) in Other Operating Liabilities (Decrease) increase in other liabilities Increase (Decrease) in Other Operating Assets Increase in other assets Increase (Decrease) in Insurance Liabilities Increase (decrease) in insurance claims Increase (Decrease) in Accounts Payable Increase in accounts payable Increase (Decrease) in Receivables Decrease (increase) in trade and other accounts receivable Amortization of Debt Issuance Costs Non-cash interest charges Increase (Decrease) in Deferred Income Taxes Deferred income taxes, net Provision for Doubtful Accounts Provisions for losses on trade and other accounts receivable Share-based Compensation Stock-based compensation Total cost of the Plans during the period Net Cash Provided by (Used in) Operating Activities NET CASH PROVIDED BY OPERATING ACTIVITIES Statement of Stockholders' Equity [Abstract] Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Retained Earnings [Member] Retained Earnings Common Stock [Member] Common Stock AOCI Attributable to Parent [Member] Accumulated Other Comprehensive (Loss) Income Accumulated Other Comprehensive Income (Loss) Treasury Stock [Member] Treasury Stock at Cost Additional Paid-in Capital [Member] Additional Paid-In Capital Adjustments for New Accounting Pronouncements [Axis] Adjustments for New Accounting Pronouncements [Axis] Type of Adoption [Domain] Type of Adoption [Domain] Treasury Stock, Value, Acquired, Cost Method Purchases of common stock Dividends, Common Stock, Cash Dividends Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Beginning Balance Ending Balance Treasury Stock, Shares, Acquired Purchases of common stock (in shares) Shares, Issued Ending Balance (in shares) Beginning Balance (in shares) Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Issuance of stock related to stock-based compensation plans Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Stock-based compensation Other Comprehensive Income (Loss), Net of Tax Other comprehensive (loss) income Stock Issued During Period, Shares, Share-based Compensation, Net of Forfeitures Issuance of stock related to stock-based compensation plans (in shares) Accounting Policies [Abstract] Significant Accounting Policies [Text Block] Significant Accounting Policies Disclosure of Compensation Related Costs, Share-based Payments [Abstract] Beginning Balance, Weighted Average Remaining Contractual Term (years) Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Share-based Payment Arrangements Income Tax Disclosure [Abstract] Income Tax Disclosure [Text Block] Income Taxes Earnings Per Share [Abstract] Class of Stock [Axis] Class of Stock [Domain] Earnings Per Share [Text Block] Earnings Per Share Supplemental Cash Flow Elements [Abstract] Cash Flow, Supplemental Disclosures [Text Block] Additional Cash Flow Information Segment Reporting [Abstract] Segment Reporting Disclosure [Text Block] Segment Information Equity [Abstract] Comprehensive Income (Loss) Note [Text Block] Other Comprehensive Income Investments, Debt and Equity Securities [Abstract] Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Investments Leases [Abstract] Disclosure Of Leases Of Lessee [Text Block] Leases Disclosure Of leases of lessee. Debt Disclosure [Abstract] Debt Disclosure [Text Block] Debt Commitments and Contingencies Disclosure [Abstract] Commitments and Contingencies Disclosure [Text Block] Commitments and Contingencies Equity Securities without Readily Determinable Fair Value, Annual Amount [Abstract] Equity Method Investments and Joint Ventures [Abstract] Equity Securities Without Readily Determinable Fair Value [Text Block] Equity investment Equity securities without readily determinable fair value text block. Revenue from Contract with Customer [Policy Text Block] Revenue from Contracts with Customers – Disaggregation of Revenue Disaggregation of Revenue [Table Text Block] Schedule of Disaggregation of Revenue Schedule of Share-based Compensation, Restricted Stock Units Award Activity [Table Text Block] Schedule of Information on Restricted Stock Units Schedule of Compensation Cost for Share-based Payment Arrangements, Allocation of Share-based Compensation Costs by Plan [Table Text Block] Amounts Recognized in Financial Statements with Respect to Plans Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block] Schedule of Information on Non-Vested Restricted Stock and Deferred Stock Units Share-based Compensation, Stock Options, Activity [Table Text Block] Summary of Information Regarding Stock Options Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Schedule of Segment Reporting Information, by Segment [Table Text Block] Information Regarding Reportable Business Segments Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Components of and Changes in Accumulated Other Comprehensive Income, Net of Related Income Taxes Schedule of Available-for-sale Securities Reconciliation [Table Text Block] Amortized Cost and Fair Value of Available-for-Sale Investments Schedule of Unrealized Loss on Investments [Table Text Block] Schedule of Unrealized Loss on Available-for-Sale Investments Finance And Operating Lease Maturity [Table Text Block] Finance And Operating Lease Maturity [Table Text Block] Represensts maturity schedule of operating and finance lease. Schedule Of Supplemental Balance Sheet Information Related To Leases [Table Text Block] Schedule Of Supplemental Balance Sheet Information Related To Leases [Table Text Block] Schedule of supplemental balance sheet information related to leases.