Document and Entity Information [Abstract] Costs and expenses: Costs and Expenses [Abstract] Selling and Marketing Expense Selling and promotional, including $447 and $401 to related parties for March 31, 2012 and 2011, respectively Selling and promotional expenses to related parties Selling and promotional expenses to related parties General and administrative General and Administrative Expense Costs and Expenses, Total Total costs and expenses Operating Income (Loss) Operating income Interest Expense Interest expense Investment Income, Interest Interest income Income (Loss) from Continuing Operations before Equity Method Investments, Income Taxes, Extraordinary Items, Cumulative Effects of Changes in Accounting Principles, Noncontrolling Interest Income before income taxes Income Tax Expense (Benefit) Income tax expense Net Income (Loss) Attributable to Parent Net income Net income Net Income Per Common Share [Abstract] Earnings per share: Earnings Per Share, Basic Basic income per share Earnings Per Share, Diluted Diluted income per share Weighted Average Number of Shares Outstanding, Diluted [Abstract] Summary of weighted average number of common shares outstanding Weighted Average Number of Shares Outstanding, Basic Basic weighted average shares outstanding Weighted Average Number of Shares Outstanding, Diluted Diluted weighted average shares outstanding Diluted weighted average shares outstanding Assets, Current [Abstract] Current assets Cash and Cash Equivalents, at Carrying Value Cash and cash equivalents, end of period Cash and cash equivalents, beginning of period Cash and cash equivalents Accounts Receivable, Net, Current Accounts receivable, net of allowance for doubtful accounts of $8,844 and $11,706 at March 31, 2012 and December 31, 2011, respectively Net of allowance for doubtful accounts Allowance for doubtful accounts Deferred Tax Assets, Net, Current Deferred income taxes Other Assets, Current Other current assets Assets, Current, Total Total current assets Property, Plant and Equipment, Net Property and equipment, net Property and equipment, net Goodwill Goodwill Other Assets, Noncurrent Other assets Assets, Total Total assets Liabilities and Stockholders' Equity [Abstract] LIABILITIES AND STOCKHOLDERS' EQUITY: Current liabilities Liabilities, Current [Abstract] Accounts payable Accounts Payable, Current Accrued Liabilities, Current Accrued liabilities Accrued Income Taxes, Current Income taxes payable Due to Related Parties, Current Due to related parties Capital Lease Obligations, Current Current portion of capital lease obligations Notes Payable, Current Current portion of notes payable Liabilities, Current, Total Total current liabilities Capital Lease Obligations, Noncurrent Capital lease obligations, less current portion Liabilities, Total Total liabilities Stockholders' Equity Attributable to Parent [Abstract] Stockholders' equity Preferred Stock, Value, Issued Preferred stock, $0.01 par value, 10,000 shares authorized; 0 shares issued and outstanding at March 31, 2012 and December 31, 2011 Preferred stock, par value Preferred stock, par value Preferred stock, shares authorized Preferred stock, shares authorized Preferred stock, shares issued Preferred stock, shares issued Preferred stock, shares outstanding Preferred stock, shares outstanding Common Stock, Value, Issued Common stock, $0.01 par value, 100,000 shares authorized; 46,147 and 45,955 shares issued and 44,490 and 44,298 shares outstanding March at 31, 2012 and December 31, 2011 respectively Common stock, par value Common stock, par value Common stock, shares authorized Common stock, shares authorized Common stock, shares issued Common stock, shares issued Common stock, shares outstanding Common stock, shares outstanding Accumulated Other Comprehensive Income (Loss), Net of Tax Accumulated other comprehensive loss Retained Earnings (Accumulated Deficit) Accumulated earnings Stockholders' Equity Attributable to Parent, Total Ending balance Beginning balance Total stockholders' equity Liabilities and Stockholders' Equity, Total Total liabilities and stockholders' equity Cash flows provided by operating activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Adjustments to reconcile net income to net cash provided by operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Share-based compensation Share-based Compensation Excess Tax Benefit from Share-based Compensation, Operating Activities Excess tax benefits from share-based compensation Amortization of Financing Costs Amortization of debt issuance costs Provision for bad debts Provision for Doubtful Accounts Depreciation, Depletion and Amortization, Nonproduction Depreciation and amortization Deferred Income Tax Expense (Benefit) Deferred income taxes Changes in assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Increase (Decrease) in Accounts Receivable Accounts receivable Increase (Decrease) in Prepaid, Deferred Expense and Other Assets Prepaid expenses and other Accounts payable Increase (Decrease) in Accounts Payable, Trade Increase (Decrease) in Accrued Liabilities Accrued liabilities and employee related liabilities Increase (Decrease) in Accrued Income Taxes Payable Income taxes receivable/payable Net Cash Provided by (Used in) Operating Activities Net cash provided by operating activities Cash flows used in investing activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Payments to Acquire Productive Assets Capital expenditures Net Cash Provided by (Used in) Investing Activities Net cash used in investing activities Cash flows provided by (used in) financing activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Payments for Repurchase of Common Stock Repurchase of common shares Excess tax benefits from share-based compensation Excess Tax Benefit from Share-based Compensation, Financing Activities Proceeds from Stock Options Exercised Net proceeds from exercise of stock options Net Cash Provided by (Used in) Financing Activities, Continuing Operations Net cash provided by (used in) financing activities Cash and Cash Equivalents, Period Increase (Decrease) Net increase (decrease) in cash and cash equivalents Supplemental disclosure of cash flow information Supplemental Cash Flow Information [Abstract] Interest Paid Cash paid for interest Income Taxes Paid Cash paid for income taxes Supplemental disclosure of non-cash investing and financing activities Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Nature of Business Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Summary of Significant Accounting Policies Significant Accounting Policies [Text Block] Earnings Per Share [Text Block] Net Income Per Common Share Valuation and Qualifying Accounts Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Property and Equipment Property, Plant and Equipment Disclosure [Text Block] Commitments and Contingencies Commitments and Contingencies Disclosure [Text Block] Income Taxes Income Tax Disclosure [Text Block] Share-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Regulatory [Text Block] Regulatory Regulatory. Amendment Flag Current Fiscal Year End Date Document Period End Date Document Type Entity Central Index Key Entity Common Stock, Shares Outstanding Entity Filer Category Entity Registrant Name Document Fiscal Period Focus Document Fiscal Year Focus Consolidated Balance Sheets [Abstract] Consolidated Income Statements [Abstract] Consolidated Statements of Cash Flows [Abstract] Consolidated Statement of Stockholders' Equity [Abstract] Shares, Issued Ending balance, shares Beginning balance, shares Other Comprehensive Income, Unrealized Gain (Loss) on Derivatives Arising During Period, Net of Tax Unrealized gain on hedging derivative, net of taxes of $20 Unrealized gains on hedging derivatives, net of taxes of $20 and $21 for March 31, 2012 and 2011, respectively Comprehensive Income, Net of Tax, Attributable to Parent Comprehensive income Stock Issued During Period, Shares, Stock Options Exercised Total Shares, exercised Exercise of stock options, shares Stock Issued During Period, Value, Stock Options Exercised Exercise of stock options Excess tax benefits from share-based compensation Adjustments to Additional Paid in Capital, Tax Effect from Share-based Compensation Stock Issued During Period, Value, Share-based Compensation Share-based compensation Other Comprehensive Income, Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Tax effect on unrealized losses on hedging derivative Tax effect on unrealized losses on hedging derivative in 2011 Common Stock [Member] Common Stock Additional Paid-in Capital [Member] Additional Paid-in Capital Accumulated Other Comprehensive Loss [Member] Accumulated Other Comprehensive Loss Accumulated Earnings [Member] Accumulated Earnings Property and Equipment [Abstract] Regulatory [Abstract] Regulatory. Statement [Table] Statement, Equity Components [Axis] Equity Component [Domain] Statement [Line Items] Share-based Compensation [Abstract] Share-based Compensation Expense Denominator [Abstract] Denominator: Denominator. Property, Plant and Equipment [Table Text Block] Property and equipment Furniture, fixtures and equipment [Member] Furniture, fixtures and equipment [Member] Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Less accumulated depreciation and amortization Property, Plant and Equipment, Gross Property and equipment Property, Plant and Equipment by Type [Axis] Property, Plant and Equipment, Type [Domain] Land and Building [Member] Land [Member] Land [Member] Land improvements [Member] Land improvements [Member] Leasehold improvements [Member] Leasehold improvements [Member] Buildings [Member] Buildings [Member] Computer equipment [Member] Computer equipment [Member] Assets Held under Capital Leases [Member] Equipment under capital leases [Member] Construction in progress [Member] Construction in progress [Member] Weighted Average Number Diluted Shares Outstanding Adjustment Effect of dilutive stock options and restricted stock Valuation Allowances and Reserves, Balance Balance at End of Period Balance at Beginning of Period Valuation Allowances and Reserves, Charged to Cost and Expense Charged to Expense Valuation Allowances and Reserves, Deductions Deductions Valuation Allowances and Reserves Type [Axis] Valuation Allowances and Reserves [Domain] Allowance for Doubtful Accounts [Member] Allowance for Doubtful Accounts [Member] Valuation and Qualifying Accounts Disclosure [Line Items] Valuation and Qualifying Accounts Disclosure [Table] Movement in Valuation Allowances and Reserves [Roll Forward] Allowance for doubtful accounts receivable: Property, Plant and Equipment [Line Items] Other Capitalized Property Plant and Equipment [Member] Other [Member] Schedule of Property, Plant and Equipment [Table] Restricted Cash and Cash Equivalents, Current Restricted cash and cash equivalents Deferred Revenue, Current Deferred revenue Student deposits Customer Deposits, Current Notes Payable, Noncurrent Notes payable, less current portion Treasury Stock, Value Treasury stock, at cost, 1,657 shares of common stock at March 31, 2012 and December 31, 2011 Treasury Stock, Shares Treasury stock, shares Treasury Stock, Value, Acquired, Cost Method Aggregate cost shares of common stock Increase (Decrease) in Customer Deposits Student deposits Increase (Decrease) in Deferred Revenue Deferred revenue Other Liabilities, Noncurrent Other noncurrent liabilities Reclassifications [Policy Text Block] Reclassifications Reclassifications. Recent Accounting Pronouncements [Policy Text Block] Recent Accounting Pronouncements Recent accounting pronouncements. Summary of Significant Accounting Policies (Textual) [Abstract] Summary of Significant Accounting Policies (Textual) [Abstract] Summary of significant accounting policies. Cost of Sales, Policy [Policy Text Block] Instructional Costs and Services Derivatives, Policy [Policy Text Block] Derivatives and Hedging Interest Rate Swap [Member] Interest Rate Swap [Member] Operating Leases of Lessee Disclosure [Table Text Block] Future minimum lease payments under operating leases Operating Leases, Future Minimum Payments Due, Current 2012 Operating Leases, Future Minimum Payments, Due in Two Years 2013 2014 Operating Leases, Future Minimum Payments, Due in Three Years 2015 Operating Leases, Future Minimum Payments, Due in Four Years 2016 Operating Leases, Future Minimum Payments, Due in Five Years Operating Leases, Future Minimum Payments, Due Thereafter Thereafter Operating Leases, Future Minimum Payments Due Total minimum Payments Operating Leases, Future Minimum Payments Due [Abstract] Future minimum lease payments under operating leases Commitments and Contingencies (Textual) [Abstract] Commitments and Contingencies (Textual) [Abstract] Commitments and contingencies. Operating Leases, Rent Expense Total rent expense and related taxes and operating expenses under operating leases Incentive Plan [Member] Incentive Plan [Member] Incentive plan. Instructional Costs and Services [Member] Instructional Costs and Services [Member] Instructional costs and services. Employee Stock Purchase Plan [Member] Employee Stock Purchase Plan [Member] Employee stock purchase plan. Share-based Compensation Arrangement by Share-based Payment Award Stock Options Disclosures [Abstract] Summary of the activity related to stock options granted under the Company's Incentive Plan Share-based compensation arrangement by Share-based payment award stock options. Total Shares outstanding, beginning balance Total Shares outstanding, ending balance Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Total Shares, granted Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period Total Shares, forfeited, canceled or expired Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Total Shares, exercisable Share-based Compensation Arrangement by Share-based Payment Award Options Available for Issuance Number Total Shares, available for issuance Share-based compensation arrangement by Share-based payment award options available for issuance number. Share Based Compensation Arrangement by Share Based Payment Award Options Outstanding Weighted Average Exercise Price Weighted Average Exercise Price per Share Outstanding, ending balance Weighted Average Exercise Price per Share Outstanding, beginning balance Weighted Average Exercise Price per Share, granted Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Exercise Price Weighted Average Exercise Price per Share, exercised Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Weighted Average Exercise Price per Share, forfeited, canceled or expired Share-based Compensation Arrangement by Share-based Payment Award, Options, Forfeitures and Expirations in Period, Weighted Average Exercise Price Weighted Average Exercise Price per Share, exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Weighted Average Remaining Contractual Term (Years), Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Intrinsic Value Aggregate Intrinsic Value, Outstanding Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Text Block] Share-based Compensation Expense Share-Based Compensation Expense Net of Tax Share-based compensation expense, net of tax Share-based compensation expense net of tax. Allocated Share-based Compensation Expense Share-based compensation expense included in operating expenses Employee Service Share-based Compensation, Tax Benefit from Compensation Expense Tax effect of share-based compensation Share-based Compensation (Textual) [Abstract] Share-based compensation. Share-based Compensation (Textual) [Abstract] Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized Common stock authorized Percentage Increase in Shares Authorized for Issuance Percentage increase in the number of shares authorized for issuance under the Incentive Plan Percentage increase in shares authorized for issuance. Value of Closing Stock Price Value of closing stock price Value of closing stock price. Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs, by Report Line [Axis] Employee Service Share-based Compensation, Allocation of Recognized Period Costs, Report Line [Domain] Selling and Marketing Expense [Member] Selling and Promotional [Member] General and Administrative Expense [Member] General and Administrative [Member] Revenues Net revenue Instructional Costs and Services Instructional costs and services Costs directly attributable to educational services, including salaries and benefits for full-time faculty, administrators and academic advisors, and costs associated with adjunct faculty. Also includes costs for educational supplies such as books, costs associated with academic records and graduation, costs associated with collections from our students such as bad debt expense, and other university services such as evaluating transcripts. Prepaid Royalties Noncurrent Prepaid royalties noncurrent. Prepaid royalties Additional Paid in Capital Additional paid-in capital Increase (Decrease) in Restricted Cash Change in restricted cash and cash equivalents Schedule of Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Table] Employee Service Share-based Compensation, Allocation of Recognized Period Costs [Line Items] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangement by Share-based Payment Award, Award Type and Plan Name [Axis] Share-based Compensation Arrangements by Share-based Payment Award, Award Type and Plan Name [Domain] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Derivative, Name [Domain] Derivative, by Nature [Axis] Derivative [Table] Derivative [Line Items] Other Comprehensive Income (Loss), Net of Tax [Abstract] Other comprehensive income, net of tax: Employee-related Liabilities, Current Accrued compensation and benefits Restricted Cash and Cash Equivalents, Noncurrent Restricted cash Income Taxes Receivable, Current Income taxes receivable Consolidated Statements of Comprehensive Income [Abstract] Treasury Stock [Member] Treasury Stock Selling and Promotional [Policy Text Block] Selling and Promotional Selling and promotional. Selling, General and Administrative Expenses, Policy [Policy Text Block] General and Administrative Revenue Recognition, Policy [Policy Text Block] Revenue Recognition Interest Expense on Derivatives Related to Credit Risk Interest expense on derivatives related to credit risk Interest expense on derivatives related to credit risk. Arrangement Expense Arrangement expense Arrangement expense. Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount University's stock options outstanding were excluded from the calculation of diluted earnings Software Development [Member] Internally developed Software [Member] Pledged Collateral as Noncurrent Restricted Cash Pledged collateral as noncurrent restricted cash Pledged collateral as noncurrent restricted cash. Reduced Pledge Collateral Reduced pledge collateral Reduced pledge collateral. Average Days from Date of Receipt in which Funds Remain as Restricted Cash and Cash Equivalents Average days from the date of receipt in which funds remain as restricted cash and cash equivalents Average days from the date of receipt in which funds remain as restricted cash and cash equivalents. Reduction in Revenue Due to Scholarships Offered to Students Reduction in revenue due to scholarships offered to students Reduction in revenue due to scholarships offered to students. Tax Effect of Share-based Compensation Expense [Abstract] Tax effect of share-based compensation Tax effect of Share-based compensation expense. Valuation and Qualifying Accounts [Table Text Block] Valuation and Qualifying Accounts Valuation and qualifying accounts. Additional Share-based Compensation (Textual) [Abstract] Share-based Compensation. Additional Share-based Compensation (Textual) [Abstract] Derivative Contract Details (Textual) [Abstract] Derivative Contract Details (Textual) [Abstract] Derivative contract. Consolidation, Policy [Policy Text Block] Principles of Consolidation Area of Company's Campus Area of the Company's campus in Phoenix, Arizona Area of the company's campus. Nature of Business (Textual) [Abstract] Nature of Business (Textual) [Abstract] Nature of business. Exit costs Exit costs Commitments and Contingencies Commitments and contingencies Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Intrinsic Value Aggregate Intrinsic Value, Exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Weighted Average Remaining Contractual Term (Years), Outstanding Nature of Business [Abstract] Summary of Significant Accounting Policies [Abstract] Commitments and Contingencies [Abstract] Share-Based Compensation [Abstract] Cash and Cash Equivalents, Restricted Cash and Cash Equivalents, Policy [Policy Text Block] Restricted Cash and Cash Equivalents Fair Value of Financial Instruments, Policy [Policy Text Block] Fair Value of Financial Instruments Use of Estimates, Policy [Policy Text Block] Use of Estimates Segment Reporting Policy [Policy Text Block] Segment Information Schedule of Weighted Average Number of Shares [Table Text Block] Schedule of Share Based Compensation Stock Options Activity [Table Text Block] Summary of the activity related to stock options granted under the Company's Incentive Plan Valuation and Qualifying Accounts [Abstract] Increase (Decrease) in Due to Related Parties, Current Due to/from related parties Summary of weighted average number of common shares outstanding Property Plant and Equipments [Abstract] Property and equipment Property plant and equipments. Income Taxes [Abstract] Accrual for Taxes Other than Income Taxes, Current Tax reserves, non-income tax related Repayments of Debt and Capital Lease Obligations Principal payments on notes payable and capital lease obligations Mind Streams [Member] Mind Streams [Member] Mind streams. Related Party Transactions, by Related Party [Axis] Related Party [Domain] Commitments and Contingencies, Policy [Policy Text Block] Commitments and Contingencies Stock Repurchase Program, Remaining Authorized Repurchase Amount Remaining authorized repurchase amount Additional Amount Authorized by Board of Directors Additional amount authorized by board of directors Additional amount authorized by board of directors. Authorized to Repurchase Common Stock Including Additional Repurchase Authorized to repurchase common stock including additional repurchase Authorized to repurchase common stock including additional repurchase. Stock Repurchase Program Authorized Amount Authorized to repurchase common stock Trade and Other Accounts Receivable, Policy [Policy Text Block] Allowance for Doubtful Accounts Percent of Financial Aid Earn by Student Percent of financial aid earn by student Percent of financial aid earn by student. Period for Write Off Inactive Student Accounts Period for write off inactive student accounts Period for write off inactive student accounts. Earnings Per Share (Textual) [Abstract] Earnings Per Share (Textual) [Abstract] Earnings per share. Expiration Date on Repurchase Authorizations Expiration date on repurchase authorizations. Expiration date on repurchase authorizations Restricted and Unrestricted Stock [Member] restricted and unrestricted stock. Restricted and Unrestricted Stock [Member] Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Total Shares, Outstanding, Ending Balance Total Shares, Outstanding, Beginning Balance Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period Total Shares, granted Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Total Shares, vested Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Total Shares, forfeited, cancelled or expired Share-based Compensation Arrangement by Share Based Payment Award Equity Instruments Other than Option Forfeited in Period Weighted Average Grant Date Fair Value Weighted Average Grant Date Fair Value, forfeited, cancelled or expired Share-based compensation arrangement by Share-based payment award equity instruments other than option forfeited in period weighted average grant date fair value. Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Weighted Average Grant Date Fair Value Weighted Average Grant Date Fair Value, Ending Balance Weighted Average Grant Date Fair Value, Beginning Balance Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Weighted Average Grant Date Fair Value, granted Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Weighted Average Grant Date Fair Value, vested Treasury Stock [Abstract] Share-based Compensation Restricted Stock Units and Unrestricted Stock Granted Under Incentive Plan Award [Abstract] Share-based compensation restricted stock units and unrestricted stock granted under the incentive plan award Share-based compensation restricted stock units and unrestricted stock granted under the incentive plan award. Summary of Activity Related to Restricted and Unrestricted Stock Granted Under Incentive Plan [Table Text Block] Summary of the activity related to restricted and unrestricted stock granted under the Incentive Plan Summary of the activity related to restricted and unrestricted stock granted under the incentive plan. Common Stock Acquired, Shares Common stock acquired, shares. Common stock acquired, shares Deferred Tax Liabilities, Noncurrent Deferred income taxes, noncurrent Increase Decrease in Deferred Rent Deferred rent Increase decrease in deferred rent. Shortfall Tax Expense from Share based Compensation Shortfall tax expense from share-based compensation. Shortfall tax expense from share-based compensation Tax Benefit of Spirit Warrant Intangible Tax benefit of Spirit warrant intangible. Tax benefit of Spirit warrant intangible Amortization of Other Current Assets Under Reclassification Amortization of other current assets under reclassification. Amortization of other current assets Purchases of Property and Equipment Included in Accounts Payable Purchases of property and equipment included in accounts payable. Purchases of property and equipment included in accounts payable Treasury Stock [Text Block] Treasury Stock Derivative, Inception Date Inception date of derivative agreements Derivative, Maturity Date Maturity date of derivative agreements Derivative Asset, Fair Value, Gross Asset Fair value of interest rate corridor included in other assets Derivative Liability, Fair Value, Gross Liability Fair value of interest rate swap is a liability, which is included in other non current liability Derivative Instruments, Loss Recognized in Other Comprehensive Income (Loss), Effective Portion Loss on derivatives included as a component of other comprehensive income, net of taxes Interest Rate Corridor [Member] Interest rate corridor. Interest Rate Corridor [Member] Notional Amount of Cash Flow Hedge Instruments Notional amount of interest rate swap Maximum Variable Interest Rate Description Interest rate payable on interest rate corridor if 30 day LIBOR is less than 4% Maximum variable interest rate on thirty day Libor. Maximum Variable Interest Rate Percentage Interest rate payable on interest rate corridor 30 day LIBOR equal to 4% through 6% Maximum variable interest rate on thirty day Libor equal to four percentage through six percentage. Variable Interest Rate Payable on Interest Rate Corridor Description Interest rate payable on interest rate corridor 30 day LIBOR exceeds 6% Maximum variable interest rate on thirty day Libor exceeds six percentage. Derivative, Fixed Interest Rate Fixed Interest rate payable on interest rate swap amortizing notional amount Derivative Variable Interest Rates Interest rate receivable on interest rate swap amortizing notional amount Derivative variable interest rates. Treasury Stock (Textual) [Abstract] Treasury stock. Treasury Stock (Textual) [Abstract] Unaudited Interim Financial Information [Policy Text Block] Unaudited Interim Financial Information Unaudited interim financial information. Designated as Hedging Instrument [Member] Designated as Hedging Instrument [Member] Hedging Designation [Axis] Hedging Designation [Domain] Gain (Loss) on Sale of Property Plant Equipment Loss on asset disposal Debt Inception Dates Debt inception dates. Debt inception dates Debt Maturity Dates Debt maturity Dates. Debt maturity Dates