Marketing Fee [Abstract] Marketing Fee [Abstract] Marketing fee receivable Marketing Fee Receivable Current This element represents marketing fees assessed on certain trades taking place at the exchange, marketing fees are made available to designated primary market makers and preferred market makers as an economic inducement to route orders. Marketing fee assessments and payments are reflected on a net basis, with no impact on revenues or expenses. Marketing fee payable Marketing Fee Payable Current This element represents marketing fee payments on certain trades taking place at the exchange, marketing fees are made available to designated primary market makers and preferred market makers as an economic inducement to route orders. Marketing fee assessments and payments are reflected on a net basis, with no impact on revenues or expenses. Earnings Per Share [Abstract] Schedule of Earnings Per Share, Basic and Diluted Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Legal Proceedings [Abstract] Legal Proceedings [Abstract] Legal Proceedings Legal Matters and Contingencies [Text Block] Condensed Consolidated Statements of Cash Flows [Abstract] Condensed Consolidated Statements of Cash Flows [Abstract] Statement [Table] Statement [Table] Statement, Scenario [Axis] Statement, Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] Statement [Line Items] Statement [Line Items] Cash Flows from Operating Activities: Net Cash Provided by (Used in) Operating Activities [Abstract] Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Adjustments to reconcile net income to net cash flows from operating activities: Adjustments to Reconcile Net Income (Loss) to Cash Provided by (Used in) Operating Activities [Abstract] Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Other amortization Amortization Provision for deferred income taxes Deferred Income Tax Expense (Benefit) Stock-based compensation Share-based Compensation Loss on disposition of property Gain (Loss) on Sale of Property Plant Equipment Equity in loss of affiliates Equity Gain Loss Investments This item represents the entity's proportionate share for the period of the net income (loss) of its investee (such as unconsolidated subsidiaries and joint ventures) to which the equity method of accounting is applied. Such amount typically reflects adjustments similar to those made in preparing consolidated statements, including adjustments to eliminate intercompany gains and losses, and to amortize, if appropriate, any difference between cost and underlying equity in net assets of the investee at the investment date. Impairment of investment in affiliate Other than Temporary Impairment Losses, Investments Changes in assets and liabilities: Increase (Decrease) in Operating Capital [Abstract] Increase (Decrease) in Restricted Cash Increase (Decrease) in Restricted Cash Accounts receivable Increase (Decrease) in Accounts Receivable Marketing fee receivable Increase Decrease In Marketing Fee Receivable The net change during the reporting period in amount due within one year (or one business cycle) from marketing fee. Income taxes receivable Increase (Decrease) in Income Taxes Receivable Prepaid expenses Increase (Decrease) in Prepaid Expense Other receivable Increase (Decrease) in Other Receivables Other current assets Increase (Decrease) in Other Operating Assets Accounts payable and accrued expenses Increase (Decrease) in Accounts Payable and Accrued Liabilities Marketing fee payable Increase Decrease In Marketing Fee Payable The net change during the reporting period in amount payable within one year (or one business cycle) for marketing fee. Increase (Decrease) in Deferred Revenue Increase (Decrease) in Deferred Revenue Post-retirement benefit obligations Increase (Decrease) in Pension and Postretirement Obligations Income taxes payable Increase (Decrease) in Income Taxes Payable Settlement with appellants Increase Decrease In Settlement With Appellants The net change during the reporting period in amount payable within one year (or one business cycle) for settlement with appellants. Access fees subject to fee-based payment Increase Decrease In Access Fees Subject To Fee Based Payment The net change during the reporting period in amount payable within one year (or one business cycle) for access fees subject to fee-based payment. Net Cash Flows provided by Operating Activities Net Cash Provided by (Used in) Operating Activities Cash Flows from Investing Activities: Net Cash Provided by (Used in) Investing Activities [Abstract] Capital and other assets expenditures Payments for (Proceeds from) Productive Assets Investment in Signal Trading Systems, LLC Payments for (Proceeds from) Investments Other Payments for (Proceeds from) Other Investing Activities Net Cash Flows used in Investing Activities Net Cash Provided by (Used in) Investing Activities Cash Flows from Financing Activities: Net Cash Provided by (Used in) Financing Activities [Abstract] Payments for debt issuance costs Payments of Debt Issuance Costs Payment of quarterly dividends Payments of Dividends Purchase of unrestricted stock from employees Purchase Of Restricted Stock From Employees Cash Flow Impact This element represents the cash outflow relating to the purchase of restricted stock from employees. Purchase of unrestricted common stock Payments for Repurchase of Common Stock Exercise right privilege payable Payments Of Exercise Right Privilege Payable The cash outflow as a result of payment of exercise right privilege payable according to the settlement agreement during the reporting period. Net proceeds from issuance of unrestricted common stock Proceeds from Issuance of Common Stock Payment of special dividend Payment Of Special Dividend This element represents the cash outflow related to the payment of special dividend. Net Cash Flows used in Financing Activities Net Cash Provided by (Used in) Financing Activities Net Increase (Decrease) in Cash and Cash Equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and Cash Equivalents at Beginning of Period Cash and Cash Equivalents, at Carrying Value Cash and Cash Equivalents at End of Period Supplemental Disclosure of Cash Flow Information Supplemental Cash Flow Information [Abstract] Cash paid for income taxes Income Taxes Paid, Net Non-cash activities: Cash Flow, Noncash Investing and Financing Activities Disclosure [Abstract] Change in post-retirement benefit obligation Defined Benefit Plan, Accumulated Benefit Obligation Unpaid liability to acquire equipment and software Noncash or Part Noncash Acquisition, Value of Assets Acquired Senior Revolving Credit Facility [Abstract] Senior Revolving Credit Facility [Abstract] Debt Disclosure [Text Block] Debt Disclosure [Text Block] Income Tax Disclosure [Abstract] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Income Tax Expense (Benefit) Income Tax Expense (Benefit) Effective Income Tax Rate, Continuing Operations Effective Income Tax Rate, Continuing Operations Income Tax Reconciliation, Deductions, Qualified Production Activities Income Tax Reconciliation, Deductions, Qualified Production Activities Income Tax Reconciliation, Tax Contingencies, State and Local Income Tax Reconciliation, Tax Contingencies, State and Local Liability for Uncertain Tax Positions, Noncurrent Liability for Uncertain Tax Positions, Noncurrent Unrecognized Tax Benefits, Reductions Resulting from Lapse of Applicable Statute of Limitations Unrecognized Tax Benefits, Reductions Resulting from Lapse of Applicable Statute of Limitations Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense Unrecognized Tax Benefits, Income Tax Penalties and Interest Expense Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Unrecognized Tax Benefits, Income Tax Penalties and Interest Accrued Employee Benefits [Abstract] Employee Benefits [Abstract] Postemployment Benefits Disclosure Postemployment Benefits Disclosure [Text Block] Accounts Payable and Accured Liabilities [Abstract] Accounts Payable and Accured Liabilities [Abstract] Employee-related Liabilities, Current Employee-related Liabilities, Current Accrued Royalties, Current Accrued Royalties, Current Accrued Expenses Facilities Accrued Expenses Facilities Total accrued expenses related to Company's facilities Accrued Legal Fees, Current Accrued Legal Fees, Current Represents accrued legal fees recorded as a current liability Accounts Payable, Current Accounts Payable, Current Liability for Treasury Shares Liability for Treasury Shares Liability for treasury shares purchased at the end of the current period that have not been settled due to three day settlement period Accrued Expense Linkage Accrued Expense Linkage Total accrued expenses related to market linkage. Other Liabilities, Current Other Liabilities, Current Accounts Payable and Accrued Liabilities Accounts Payable and Accrued Liabilities Share Repurchase Program [Abstract] Reflects shares purchased under the share repurchase program. Share Repurchase Program Share Repurchase Program [Text Block] Share Repurchase Program [Text Block] Marketing Fees Marketing Fees [Text Block] CBOE facilitates the collection and payment of marketing fees assessed on certain trades taking place at the exchange. Funds resulting from the marketing fees are made payable to Designated Primary Market Makers and Preferred Market makers as an economic inducement to route orders to CBOE. The company reflects the assessments and payments on a net basis, with no impact on revenues and expenses. Share-based Compensation [Abstract] Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity Schedule of Share-based Compensation, Restricted Stock and Restricted Stock Units Activity [Table Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Basis of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Deferred Revenue [Abstract] Deferred Revenue, by Arrangement, Disclosure Deferred Revenue, by Arrangement, Disclosure [Table Text Block] Condensed Consolidated Balance Sheets [Abstract] Condensed Consolidated Balance Sheets [Abstract] Unrestricted Common Stock Unrestricted Common Stock [Member] This element represents classification of common stock as unrestricted common stock. Common Class A2 Common Class A2 [Member] This element represents classification of common stock as class A 2. Assets Assets [Abstract] Current Assets: Assets, Current [Abstract] Cash and cash equivalents Restricted Cash and Cash Equivalents, Current Restricted Cash and Cash Equivalents, Current Accounts receivable—net allowances of $331 and $304 Accounts Receivable, Net, Current Income taxes receivable Income Taxes Receivable Other prepaid expenses Other Prepaid Expense, Current Other current assets Other Assets, Current Total Current Assets Assets, Current Investments in Affiliates Equity Method Investments Land Land Property and Equipment: Property, Plant and Equipment, Gross [Abstract] Construction in progress Construction in Progress, Gross Building Buildings and Improvements, Gross Furniture and equipment Furniture and Fixtures, Gross Less accumulated depreciation and amortization Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Total Property and Equipment—Net Property, Plant and Equipment, Net Other Assets: Finite-Lived Intangible Assets, Gross [Abstract] Software development work in progress Finite Lived Software Developmen tWork In Progress This element represents the carrying amount at the balance sheet date of internal use software under development on projects that have not been completed and are not ready to be placed into service. Data processing software and other assets (less accumulated amortization of $131,153 and $121,173) Finite Lived Data Processing Software And Other Asset This element represents the net carrying amount after accumulated amortization as of the balance sheet date of capitalized costs to ready software for sale or licensing, or for long-term internal use and it also includes other assets. Total Other Assets—Net Finite-Lived Intangible Assets, Net Total Assets Liabilities and Stockholders' Equity Liabilities and Equity [Abstract] Current Liabilities: Liabilities, Current [Abstract] Accounts payable and accrued expenses Accounts Payable and Accrued Liabilities, Current Deferred revenue and other liabilities Deferred Revenue, Current Post-retirement medical benefits Post Retirement Medical Benefits Current This element represents the carrying amount as of the balance sheet date of the portion of the obligations recognized for the medical benefits provided to former or inactive employees, their beneficiaries, and covered dependents after retirement that is payable within one year of the balance sheet date. Income tax payable Accrued Income Taxes, Current Total Current Liabilities Liabilities, Current Long-term Liabilities: Liabilities, Noncurrent [Abstract] Post-retirement medical benefits Post Retirement Medical Benefits Noncurrent This element represents the carrying amount as of the balance sheet date of the portion of the obligations recognized for the medical benefits provided to former or inactive employees, their beneficiaries, and covered dependents after retirement that is payable after one year (or beyond the operating cycle if longer). Income taxes payable Accrued Income Taxes, Noncurrent Other long-term liabilities Other Liabilities, Noncurrent Deferred income taxes Deferred Income Tax Liabilities Total Long-term Liabilities Liabilities, Noncurrent Commitments and Contingencies Commitments and Contingencies Total Liabilities Liabilities Stockholders’ Equity: Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, $0.01 par value: 20,000,000 shares authorized, no shares issued and outstanding at September 30, 2012 and December 31, 2011 Preferred Stock, Value, Issued Common Stock, Value, Issued Common Stock, Value, Issued Additional paid-in-capital Additional Paid in Capital, Common Stock Retained earnings Retained Earnings (Accumulated Deficit) Treasury stock at cost – 3,998,564 shares at September 30, 2012 and 2,012,337 shares at December 31, 2011 Treasury Stock, Value Accumulated other comprehensive loss Accumulated Other Comprehensive Income (Loss), Net of Tax Total Stockholders’ Equity Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Liabilities and Stockholders’ Equity Liabilities and Equity Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Grants in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Total Fair Value Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized Employee Service Share-based Compensation, Nonvested Awards, Total Compensation Cost Not yet Recognized Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Remaining Contractual Term Condensed Consolidated Statements of Stockholders’ Equity [Abstract] Condensed Consolidated Statements of Stockholders’ Equity [Abstract] Report Date [Axis] Report Date [Axis] Financial Statements Date [Domain] Financial Statements Date [Domain] Statement, Equity Components [Axis] Statement, Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Preferred Stock Preferred Stock [Member] Additional Paid-in Capital Additional Paid-in Capital [Member] Retained Earnings Retained Earnings [Member] Treasury Stock Treasury Stock [Member] Accumulated Other Comprehensive Income (Loss) Accumulated Other Comprehensive Income (Loss) [Member] Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Beginning of Period Automatic Conversion Of Shares In Unrestricted Common Stock And Sale Of That In IPO Automatic Conversion Of Shares In Unrestricted Common Stock And Sale Of That In IPO This element represents the automatic conversion of the shares of Class A and Class B common stock, not converted into unrestricted common stock, and sold in the initial public offering into Class A-1 and A-2 common stock Dividends, Common Stock, Cash Dividends, Common Stock, Cash Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Adjustments to Additional Paid in Capital, Share-based Compensation, Requisite Service Period Recognition Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Stock Issued During Period, Value, Share-based Compensation, Net of Forfeitures Purchase Of Unrestricted Stock From Employees Purchase Of Restricted Stock From Employees This element represents the adjustment made to the treasury stock relating to the purchase of restricted stock from employees. Purchase Of Unrestricted Common Stock Purchase Of Unrestrcited Common Stock Reflects purchases of unrestricted common stock. Post-retirement benefit obligation adjustments- net of tax Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Comprehensive Income Other Comprehensive Income (Loss), Net of Tax Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest End of Period Stock Repurchase Program, Authorized Amount Stock Repurchase Program, Authorized Amount Treasury Stock, Shares, Acquired Stock Repurchased During Period, Shares Treasury Stock Acquired, Average Cost Per Share Treasury Stock Acquired, Average Cost Per Share Treasury Stock, Value, Acquired, Cost Method Treasury Stock, Value, Acquired, Cost Method Treasury Stock, Shares Stock Repurchase Program, Total Acquired Total shares acquired by the Company under announced repurchase program Treasury Stock Acquired,Cost Per Share Treasury Stock Acquired,Cost Per Share The cost per share of shares purchased under the program announced in August 2011 Treasury Shares, Acquired, Value Treasury Shares, Acquired, Value The total value of shares acquired under the program announced in August 2011 Condensed Consolidated Statement of Comprehnsive Income [Abstract] Condensed Consolidated Statement of Comprehnsive Income [Abstract] Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Undistributed Earnings Allocated to Participating Securities Undistributed Earnings Allocated to Participating Securities Comprehensive Income (Loss), Net of Tax, Attributable to Parent Comprehensive Income (Loss), Net of Tax, Attributable to Parent Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, Number Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Nonvested, 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 Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Vested in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Share-based Compensation Arrangement by Share-based Payment Award, Equity Instruments Other than Options, Forfeited in Period Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Share-based Compensation Arrangement by Share-based Payment Award, Options, Grants in Period, Weighted Average Grant Date Fair Value Subsequent Events [Abstract] Fair Value Disclosures [Abstract] Money Market Funds, at Carrying Value Money Market Funds, at Carrying Value Assets, Fair Value Disclosure Assets, Fair Value Disclosure Defined Benefit Plan, Contributions by Employer Defined Benefit Plan, Contributions by Employer Pension and Other Postretirement Benefit Contributions Pension and Other Postretirement Benefit Contributions Schedule of Accounts Payable and Accrued Liabilities Schedule of Accounts Payable and Accrued Liabilities [Table Text Block] Fair Value Disclosures Fair Value Disclosures [Text Block] Fair Value, Measurement Inputs, Disclosure Fair Value, Measurement Inputs, Disclosure [Table Text Block] Net Income Allocated to Common Stockholders Net Income (Loss) Available to Common Stockholders, Basic Weighted Average Number of Shares Outstanding, Basic Weighted Average Number of Shares Outstanding, Basic Weighted Average Number of Shares Outstanding, Diluted Weighted Average Number of Shares Outstanding, Diluted Weighted Average Number Diluted Shares Outstanding Adjustment Weighted Average Number Diluted Shares Outstanding Adjustment Earnings Per Share, Basic Earnings Per Share, Basic Earnings Per Share, Diluted Earnings Per Share, Diluted Investment in Affiliates [Abstract] Investment in Affiliates [Abstract] Investments in and Advances to Affiliates Investments in and Advances to Affiliates [Table Text Block] Accounts Payable and Accrued Liabilities Accounts Payable and Accrued Liabilities Disclosure [Text Block] Investment in Affiliates [Axis] Investment in Affiliates [Axis] Investment in Affiliates [Axis] Investment in Affiliates [Domain] Investment in Affiliates [Domain] Investment in Affiliates [Domain] Investment in OCC [Member] Investment in OCC [Member] Investment in OCC [Member] Investment in Signal Trading [Member] Investment in Signal Trading [Member] Investment in Signal Trading [Member] Investment in IPXI [Member] Investment in IPXI [Member] Investment in IPXI [Member] Investments in Affiliates Investments in and Advances to Affiliates, Balance, Principal Amount New Income per Common Share Earnings Per Share [Text Block] Declared Dividends Per Share Declared Dividends Per Share Declared Dividends Per Share Investments in Affiliates Investments in and Advances to Affiliates, Schedule of Investments [Text Block] Subsequent Events Subsequent Events [Text Block] Liquidity Provider [Axis] Liquidity Provider [Axis] Cash additions and amortization of liquidity provider sliding scale Liquidity Provider [Domain] Liquidity Provider [Domain] Liquidity Provider [Domain] Liquidity Provider Cash Received [Member] Liquidity Provider Cash Received [Member] Cash payments from liquidity providers for LP sliding scale. Liquidity Provider Revenue Recognized [Member] Liquidity Provider Revenue Recognized [Member] Amortization of cash payments from liquidity providers for LP sliding scale. Other Deferred Revenue [Axis] Other Deferred Revenue [Axis] Other Deferred Revenue [Axis] Other Deferred Revenue [Domain] Other Deferred Revenue [Domain] Other Deferred Revenue [Domain] Other Deferred Revenue [Member] Other Deferred Revenue [Member] Other Deferred Revenue [Member] Other Deferred Revenue Cash Received [Member] Other Deferred Revenue Cash Received [Member] Other Deferred Revenue Cash Received [Member] Other Deferred Revenue Recognized [Member] Other Deferred Revenue Recognized [Member] Other Deferred Revenue Recognized [Member] Liquidity Provider Transaction Fee Sliding Scale, Monthly Contract Volume for Reduced Fees, Minimum Liquidity Provider Transaction Fee Sliding Scale, Monthly Contract Volume for Reduced Fees, Minimum Liquidity Provider Transaction Fee Sliding Scale, Monthly Contract Volume for Reduced Fees, Minimum Deferred Revenue Deferred Revenue Increase (Decrease) in Deferred Revenue and Customer Advances and Deposits Increase (Decrease) in Deferred Revenue and Customer Advances and Deposits Deferred Revenue, Period Increase (Decrease) Deferred Revenue, Period Increase (Decrease) Other than Temporary Impairment Losses, Investments Cost Method Investment, Ownership Percentage Cost Method Investment, Ownership Percentage Percent ownership of costs metohd investment. Payments for (Proceeds from) Investments Due to Affiliate, Current Due to Affiliate, Current Cost Method Investment, Ownership Percentage, Other Cost Method Investment, Ownership Percentage, Other Cost Method Investment, Ownership Percentage, Other Income Taxes Income Tax Disclosure [Text Block] Condensed Consolidated Statement of Income [Abstract] Condensed Consolidated Statement of Income [Abstract] Operating Revenues: Revenues [Abstract] Transaction fees Transaction Fees This element represents total transaction fees charged per contract during the reporting period. Access fees Access Fees This element represents revenue from fees assessed to customers for the use of the trading floor and electronic access. Exchange services and other fees Exchange Services And Other Fees This element represents revenue from fees assessed to customers for the use of the trading floor and electronic access. Market data fees Market Data Fees This element represents income derived from the entity's share of Options Price Reporting Authority income and sale of reporting entity's transaction information through market data services. Regulatory fees Regulatory Fees This element represents income derived from charges to trading permit holders and trading permit holder firms in support of CBOE?s regulatory responsibilities as a self regulatory organization. Other revenue Other Revenue, Net Total Operating Revenues Revenues Operating Expenses: Operating Expenses [Abstract] Employee costs Labor and Related Expense Data processing Information Technology and Data Processing Outside services Professional Fees Royalty fees License Costs Trading volume incentives Trading Volume Incentives This element represents expenses for customer orders routed to competing exchanges and market maker incentives for transactions in a penny pilot class. Travel and promotional expenses Travel and Entertainment Expense Facilities costs Occupancy, Net Other expenses Other Expenses Total Operating Expenses Operating Expenses Operating Income Operating Income (Loss) Other Income/(Expense): Other Nonoperating Income (Expense) [Abstract] Investment income Investment Income, Net Net loss from investment in affiliates Income (Loss) from Equity Method Investments Interest and other borrowing costs Interest and Debt Expense Total Other Income/(Expense) Other Nonoperating Income (Expense) Income Before Income Taxes Income Loss From Continuing Operations Before Income Taxes Minority Interest And After Income Loss From Equity Method Investments This element refers to the sum of operating profit and nonoperating income (expense) before income taxes, extraordinary items, and cumulative effects of changes in accounting principles, and noncontrolling interest but after income (loss) from equity method investments. Income tax provision Net Income (Loss), Including Portion Attributable to Noncontrolling Interest Net income per share (Note 4): Weighted average shares used in computing income per share: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic Stock-Based Compensation Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Description of Business [Abstract] Description of Business [Abstract] Description Of Business Description Of Business Conversion Dividend Payment And Initial Public Offering Disclosure [Text Block] This element represents disclosure in respect to the primary business of the reporting entity, conversion of the reporting entity from a non-stock corporation, owned by its members into a stock corporation; payment of a special dividend on common stock and the initial public offering. Deferred Revenue Deferred Revenue Disclosure [Text Block] Document and Entity Information [Abstract] Document and Entity Information [Abstract] Entities [Table] Entities [Table] Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] Entity Information [Line Items] Entity Information [Line Items] Entity Registrant Name Entity Registrant Name Entity Central Index Key Entity Central Index Key Current Fiscal Year End Date Current Fiscal Year End Date Entity Filer Category Entity Filer Category Document Type Document Type Document Period End Date Document Period End Date Document Fiscal Year Focus Document Fiscal Year Focus Document Fiscal Period Focus Document Fiscal Period Focus Amendment Flag Amendment Flag Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Entity Well-known Seasoned Issuer Entity Well-known Seasoned Issuer Entity Voluntary Filers Entity Voluntary Filers Entity Current Reporting Status Entity Current Reporting Status Entity Public Float Entity Public Float Condensed Consolidated Statements of Stockholders’ Equity Parenthetical [Abstract] Condensed Consolidated Statements of Stockholders’ Equity Parenthetical [Abstract] Post-retirement benefit obligation adjustment, tax expense Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax Condensed Consolidated Balance Sheets Parenthetical [Abstract] Condensed Consolidated Balance Sheets Parenthetical [Abstract] Accounts receivable, allowances (in dollars) Allowance for Doubtful Accounts Receivable, Current Other Assets: Other Assets, Noncurrent [Abstract] Data processing software and other assets, accumulated amortization (in dollars) Finite-Lived Intangible Assets, Accumulated Amortization Shareholders' Equity: Statement of Stockholders' Equity [Abstract] Preferred stock, par value Preferred Stock, Par or Stated Value Per Share 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, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized Common Stock, Shares Authorized Common stock, shares issued Common Stock, Shares, Issued Common stock, shares outstanding Common Stock, Shares, Outstanding Treasury Stock at Cost Treasury Stock, Shares