Goodwill and Intangible Assets Disclosure [Abstract] Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets by Major Class [Axis] Finite-Lived Intangible Assets, Major Class Name [Domain] Finite-Lived Intangible Assets, Major Class Name [Domain] Clearing Firm, Market Data And Other Customer Relationships [Member] Customer Relationships [Member] Technology-Related Intellectual Property [Member] Developed Technology Rights [Member] Total Amortizable Intangible Assets [Member] Finite-Lived Intangible Assets [Member] Other Intangible Assets [Member] Other Intangible Assets [Member] Indefinite-lived Intangible Assets by Major Class [Axis] Indefinite-lived Intangible Assets [Axis] Indefinite-lived Intangible Assets, Major Class Name [Domain] Indefinite-lived Intangible Assets, Major Class Name [Domain] Trade Names [Member] Trade Names [Member] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets [Line Items] Finite-Lived Intangible Assets, Gross Finite-Lived Intangible Assets, Gross Accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Net book value Finite-Lived Intangible Assets, Net Indefinite-lived Intangible Assets Indefinite-Lived Intangible Assets (Excluding Goodwill) Other Indefinite-lived Intangible Assets Other Indefinite-lived Intangible Assets Guarantees [Abstract] Guarantees Guarantees [Text Block] Accumulated Other Comprehensive Income (Loss), Net of Tax [Abstract] Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Statement of Stockholders' Equity [Abstract] Statement [Table] Statement [Table] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Class A Common Stock [Member] Common Class A [Member] Class B Common Stock [Member] Common Class B [Member] Statement, Equity Components [Axis] Equity Components [Axis] Equity Component [Domain] Equity Component [Domain] Common Stock And Additional Paid-In Capital [Member] Common Stock Including Additional Paid in Capital [Member] Retained Earnings [Member] Retained Earnings [Member] Accumulated Other Comprehensive Income (Loss) [Member] AOCI Attributable to Parent [Member] Parent [Member] Parent [Member] Noncontrolling Interest [Member] Noncontrolling Interest [Member] Statement [Line Items] Statement [Line Items] Balance (in shares) Common Stock, Shares, Outstanding Balance Stockholders' Equity Attributable to Parent Stockholders' Equity Attributable to Noncontrolling Interest Stockholders' Equity Attributable to Noncontrolling Interest Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Net Income Attributable to CME Group Net Income (Loss) Attributable to Parent Net Income (Loss) Attributable to Noncontrolling Interest Net Income (Loss) Attributable to Noncontrolling Interest Net income Net income including portion attributable to nonredeemable non-controlling interest Net income including portion attributable to nonredeemable non-controlling interest Other Comprehensive Income (Loss), Net of Tax Other Comprehensive Income (Loss), Net of Tax Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Dividends on common stock per share Dividends, Cash Adjustments to Additional Paid in Capital, Other Adjustments to Additional Paid in Capital, Other Exercise of stock options (in shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercises in Period Exercise of stock options Stock Issued During Period, Value, Stock Options Exercised Excess tax benefits from option exercises and restricted stock vesting Adjustments to Additional Paid in Capital, Income Tax Benefit from Share-based Compensation Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Stock Issued During Period, Shares, Restricted Stock Award, Net of Forfeitures Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Stock Issued To Related Parties During Period Shares Stock Issued To Related Parties During Period Shares Number of shares of stock issued during the period to related parties. Stock Issued To Related Parties During Period Value Stock Issued To Related Parties During Period Value Value of stock issued during the period to related parties. Stock Issued During Period, Shares, Employee Stock Purchase Plans Stock Issued During Period, Shares, Employee Stock Purchase Plans Stock Issued During Period, Value, Employee Stock Purchase Plan Stock Issued During Period, Value, Employee Stock Purchase Plan Stock Granted, Value, Share-based Compensation, Gross Stock Granted, Value, Share-based Compensation, Gross Stockholders' Equity Attributable to Noncontrolling Interest Balance (in shares) Balance Intangible Assets And Goodwill Goodwill and Intangible Assets Disclosure [Text Block] Investments, All Other Investments [Abstract] Investments and Other Noncurrent Assets [Text Block] Investments and Other Noncurrent Assets [Text Block] Fair Value, Assets, Liabilities and Stockholders' Equity Measured on Recurring Basis [Abstract] Financial instruments measured at fair value on a recurring basis Fair Value, Measurement Inputs, Disclosure [Text Block] Reconciliation of assets and liabilities valued at fair value on a recurring basis using significant unobservable inputs (level 3) Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block] Fair value of Debt Instruments [Table Text Block] Fair value of Debt Instruments [Table Text Block] [Table Text Block] for Fair value of Debt Instruments [Table] Debt Disclosure [Abstract] Debt Instrument [Axis] Debt Instrument [Axis] Debt Instrument, Name [Domain] Debt Instrument, Name [Domain] $612.5 million fixed rate notes due March 2018, interest equal to 4.40% [Member] Six Hundred Twelve Point Five Million Fixed Rate Notes Due March Two Thousand Eighteen, Interest Equal To Four Point Four Zero Percent [Member] $612.5 Million Fixed Rate Notes Due March 2018, Interest Equal To 4.40% $750 Million Fixed Rate Notes Due March 2022, Interest Equal To 3.0% [Member] Seven Hundred Fifty Million Fixed Rate Notes Due March Two Thousand Twenty Two, Interest Equal To Three Point Zero Percent [Member] [Member] Seven Hundred Fifty Million Fixed Rate Notes Due March Two Thousand Twenty Two, Interest Equal To Three Point Zero Percent [Member] [Member] $750.0 Million Fixed Rate Notes Due March 2025, Interest Equal To 3.00% $750.0 Million Fixed Rate Notes Due March 2025, Interest Equal To 3.00% [Member] Seven Hundred Fifty Million Fixed Rate Notes Due March Two Thousand Twenty Five, Interest Equal To Three Point Zero Percent [Member] [Member] [Member] $750.0 Million Fixed Rate Notes Due March 2043, Interest Equal To 5.3% [Member] Seven Hundred Fifty Million Fixed Rate Notes Due March Two Thousand Forty Three, Interest Equal To Five Point Three Percent [Member] Seven Hundred Fifty Million Fixed Rate Notes Due March Two Thousand Forty Three, Interest Equal To Five Point Three Percent Debt Instrument [Line Items] Debt Instrument [Line Items] Long-term debt Unsecured Long-term Debt, Noncurrent Forward starting interest rate swap agreement fixed rate Forward starting interest rate swap agreement fixed rate Forward starting interest rate swap agreement, fixed rate Debt Instrument, Face Amount Debt Instrument, Face Amount Debt Instrument, Maturity Date Debt Instrument, Maturity Date Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Performance Bonds and Guaranty Fund Contributions [Abstract] Performance Bonds and Guaranty Fund Contributions [Abstract] Performance Bonds and Guaranty Fund Contributions [Text Block] Performance Bonds and Guaranty Fund Contributions [Text Block] Performance Bonds and Guaranty Fund Contributions [Text Block] Fair Value Disclosures [Abstract] Fair Value, Hierarchy [Axis] Fair Value, Hierarchy [Axis] Fair Value Hierarchy [Domain] Fair Value Hierarchy [Domain] Fair Value, Inputs, Level 3 [Member] Fair Value, Inputs, Level 3 [Member] Fair Value by Measurement Frequency [Axis] Measurement Frequency [Axis] Fair Value, Measurement Frequency [Domain] Fair Value, Measurement Frequency [Domain] Fair Value, Measurements, Recurring [Member] Fair Value, Measurements, Recurring [Member] Contingent consideration at Fair Value Business Combination, Contingent Consideration, Liability Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation, Calculation [Roll Forward] Included in operating expense Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings Schedule Of Short-Term And Long-Term Debt Schedule of Long-term Debt Instruments [Table Text Block] Long-term debt maturities at par value Schedule of Maturities of Long-term Debt [Table Text Block] 2016 Long-term Debt, Maturities, Repayments of Principal in Next Twelve Months 2017 Long-term Debt, Maturities, Repayments of Principal in Year Two 2018 Long-term Debt, Maturities, Repayments of Principal in Year Three 2019 Long-term Debt, Maturities, Repayments of Principal in Year Four 2020 Long-term Debt, Maturities, Repayments of Principal in Year Five Thereafter Long-term Debt, Maturities, Repayments of Principal after Year Five Loss Contingency [Abstract] Accrued liability related to all outstanding legal matters Estimated Litigation Liability Schedule of Guarantor Obligations [Table] Schedule of Guarantor Obligations [Table] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Axis] Guarantor Obligations, Nature [Domain] Guarantor Obligations, Nature [Domain] Family Farmer and Ranchers Protection Fund [Member] Family Farmer and Ranchers Protection Fund [Member] Family Farmer and Ranchers Protection Fund [Member] Guarantor Obligations [Line Items] Guarantor Obligations [Line Items] Agreement automatic renewal period (in years) Agreement Automatic Renewal, Period Agreement Automatic Renewal, Period Contingent liability to SGX, amount of irrevocable letters of credit Guarantee Collateral Guarantee Collateral Payment per participant PaymentPerParticipant PaymentPerParticipant Payment per cooperative PaymentPerCooperative PaymentPerCooperative FutureLosses FutureLosses FutureLosses Payments under Guarantee Payments under Guarantee Payments under Guarantee Guarantor Obligations, Maximum Exposure, Undiscounted Guarantor Obligations, Maximum Exposure, Undiscounted Organization, Consolidation and Presentation of Financial Statements [Abstract] Basis Of Presentation Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Subsequent Events [Abstract] Subsequent Events Subsequent Events [Text Block] Schedule of Defined Benefit Plans Disclosures [Table] Schedule of Defined Benefit Plans Disclosures [Table] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 1 [Member] Fair Value, Inputs, Level 2 [Member] Fair Value, Inputs, Level 2 [Member] Schedule of Trading Securities and Other Trading Assets, Major Types of Trading Securities and Assets [Axis] Major Types of Debt and Equity Securities [Axis] Major Types of Trading Securities and Assets [Domain] Major Types of Debt and Equity Securities [Domain] US Treasury Securities [Member] US Treasury Securities [Member] Asset Backed Securities [Member] Asset-backed Securities [Member] Exchange Traded Funds [Member] Exchange Traded Funds [Member] Equity Securities [Member] Equity Securities [Member] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Fair Value, Balance Sheet Grouping, Financial Statement Captions [Line Items] Available-for-sale Securities at Fair Value Available-for-sale Securities Trading Securities at Fair Value Trading Securities Marketable Securities Marketable Securities Good Faith and Margin Deposits with Broker-Dealers Good Faith and Margin Deposits with Broker-Dealers Investment Owned, at Fair Value Investment Owned, at Fair Value Total Assets at Fair Value Assets, Fair Value Disclosure Total liabilities at fair value Financial and Nonfinancial Liabilities, Fair Value Disclosure Cash dividends on common stock, per share (in dollars per share) Common Stock, Dividends, Per Share, Cash Paid Earnings Per Share [Abstract] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table Text Block] Basic And Diluted Earnings Per Share Schedule of Earnings Per Share, Basic and Diluted [Table Text Block] Fair Value Measurements, Recurring and Nonrecurring [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Minimum [Member] Minimum [Member] Maximum [Member] Maximum [Member] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items] Valuation model discount rate Fair Value Inputs, Discount Rate Valulation Model Probability Low Range Valulation Model Probability Low Range Valulation Model Probability Low Range Valuation Model Probability High Range Valuation Model Probability High Range Valuation Model Probability High Range Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Axis] Other Comprehensive Income Location [Domain] Other Comprehensive Income Location [Domain] Accumulated Translation Adjustment [Member] Accumulated Foreign Currency Adjustment Attributable to Parent [Member] Investment Securities [Member] Securities Investment [Member] Derivative Financial Instruments, Assets [Member] Derivative Financial Instruments, Assets [Member] Pension Plans, Defined Benefit [Member] Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Reclassification adjustment for loss included in net income Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Reclassification from Accumulated Other Comprehensive Income, Current Period, before Tax Net unrealized holding gains arising during the period Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Net Unamortized Gain (Loss) Arising During Period, Net of Tax Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax Net unrealized holding losses arising during the period Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax Foreign currency translation adjustment Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Comprehensive Income Before Reclassification Adjustments Other Comprehensive Income (Loss), before Reclassifications, before Tax Reclassification adjustment for gains included in investment income Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, before Tax Amortization of net actuarial (gains) losses included in pension expense Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, before Tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI on Derivatives, before Tax Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax Defined benefit plans, income tax benefit (expense) Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Tax Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, Tax Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax Comprehensive Income, Tax Other Comprehensive Income (Loss), Tax Statement of Financial Position [Abstract] Preferred Stock [Member] Preferred Stock [Member] Series A Junior Participating Preferred Stock [Member] Series A Preferred Stock [Member] Accounts receivable, allowance Allowance for Doubtful Accounts Receivable, Current Restricted cash, current Restricted Cash and Cash Equivalents, Current Accumulated depreciation and amortization, property Accumulated Depreciation, Depletion and Amortization, Property, Plant, and Equipment Restricted cash, noncurrent Restricted Cash and Cash Equivalents, Noncurrent Preferred stock, par value (in dollars per share) Preferred Stock, Par or Stated Value Per Share Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Preferred stock, shares issued (in shares) Preferred Stock, Shares Issued Preferred stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Common stock, par value (in dollars per share) Common Stock, Par or Stated Value Per Share Common stock, shares authorized (in shares) Common Stock, Shares Authorized Common stock, shares issued (in shares) Common Stock, Shares, Issued Common stock, shares outstanding (in shares) Debt Instrument, Fair Value Disclosure Debt Instrument, Fair Value Disclosure Statement of Cash Flows [Abstract] Cash Flows from Operating Activities Net Cash Provided by (Used in) Operating Activities [Abstract] Net income Net Income (Loss), Including Portion Attributable to Noncontrolling Interest 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] Stock-based compensation Share-based Compensation Amortization of purchased intangibles Amortization of Intangible Assets Depreciation and amortization Depreciation, Depletion and Amortization, Nonproduction Gain (Loss) on Sale of Investments Gain (Loss) on Sale of Investments Gains (Losses) on Extinguishment of Debt Gains (Losses) on Extinguishment of Debt Income (Loss) from Equity Method Investments, Net of Dividends or Distributions Income (Loss) from Equity Method Investments, Net of Dividends or Distributions Deferred income taxes Deferred Income Tax Expense (Benefit) Change in: Increase (Decrease) in Operating Capital [Abstract] Accounts receivable Increase (Decrease) in Accounts Receivable Other current assets Increase (Decrease) in Prepaid Expense and Other Assets Other assets Increase (Decrease) in Other Operating Assets Accounts payable Increase (Decrease) in Accounts Payable Income taxes payable Increase (Decrease) in Income Taxes Payable Other current liabilities Increase (Decrease) in Other Accrued Liabilities Other liabilities Increase (Decrease) in Other Operating Liabilities Other Other Noncash Income (Expense) Net Cash 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] Proceeds from maturities of available-for-sale marketable securities Proceeds from Maturities, Prepayments and Calls of Available-for-sale Securities Purchases of available-for-sale marketable securities Payments to Acquire Available-for-sale Securities Purchases of property Payments to Acquire Property, Plant, and Equipment Proceeds from sale of building property Proceeds from Sale of Property, Plant, and Equipment Payments to Acquire Investments Payments to Acquire Investments Proceeds from Sale of Available-for-sale Securities, Equity Proceeds from Sale of Available-for-sale Securities, Equity Settlement of derivative related to debt issuance Payments for (Proceeds from) Derivative Instrument, Investing Activities Net Cash 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] Proceeds from other borrowings, net of issuance costs Proceeds from Issuance of Long-term Debt Repayment of other borrowings Repayments of Long-term Debt Cash dividends Payments of Dividends Proceeds from exercise of stock options Proceeds from Stock Options Exercised Excess tax benefits related to employee option exercises and restricted stock vesting Excess Tax Benefit from Share-based Compensation, Financing Activities Proceeds from (Payments for) Other Financing Activities Proceeds from (Payments for) Other Financing Activities Net Cash Used in Financing Activities Net Cash Provided by (Used in) Financing Activities Net change in cash and cash equivalents Cash and Cash Equivalents, Period Increase (Decrease) Cash and cash equivalents, beginning of period Cash and Cash Equivalents, at Carrying Value Cash and Cash Equivalents, End of Period Supplemental Disclosure of Cash Flow Information Supplemental Cash Flow Information [Abstract] Income taxes paid Income Taxes Paid Interest paid Interest Paid Schedule of Accumulated Other Comprehensive Income (Loss) [Table Text Block] Comprehensive Income (Loss) Note [Text Block] Contingencies Contingencies Disclosure [Text Block] Assets Assets [Abstract] Cash and cash equivalents Marketable securities Marketable Securities, Current Accounts receivable, net of allowance Accounts Receivable, Net, Current Other current assets Other Assets, Current Cash performance bonds and guaranty fund contributions Total current assets Assets, Current Property, net of accumulated depreciation and amortization Property, Plant and Equipment, Net Intangible assets - trading products Intangible assets - other, net Intangible Assets, Net (Excluding Goodwill) Goodwill Goodwill Other assets Other Assets, Noncurrent Total Assets Assets Liabilities and Shareholders' Equity Liabilities and Equity [Abstract] Accounts payable Accounts Payable, Current Other current liabilities Other Liabilities, Current Cash performance bonds and guaranty fund contributions Margin Deposits And Guaranty Funds Liabilities Current Margin Deposits And Guaranty Funds Liabilities Current. Total current liabilities Liabilities, Current Deferred income tax liabilities, net Deferred Tax Assets, Net, Noncurrent Other liabilities Other Liabilities, Noncurrent Total Liabilities Liabilities Shareholders' Equity: Stockholders' Equity Attributable to Parent [Abstract] Preferred stock, $0.01 par value, 10,000 shares authorized, none issued or outstanding Preferred Stock, Value, Issued Common stock Common Stock, Value, Outstanding Additional paid-in capital Additional Paid in Capital, Common Stock Retained earnings Retained Earnings (Accumulated Deficit) Accumulated other comprehensive income (loss) Accumulated Other Comprehensive Income (Loss), Net of Tax Total Shareholders' Equity Total Liabilities and Shareholders' Equity Liabilities and Equity Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Schedule of Antidilutive Securities Excluded from Computation of Earnings Per Share [Table] Antidilutive Securities Excluded from Computation of Earnings Per Share, by Antidilutive Securities [Axis] Antidilutive Securities [Axis] Antidilutive Securities, Name [Domain] Antidilutive Securities, Name [Domain] Stock Options [Member] Employee Stock Option [Member] Restricted Stock [Member] Restricted Stock [Member] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items] Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Antidilutive Securities Excluded from Computation of Earnings Per Share, Amount Amortization of purchased intangibles Components of intangible assets Intangible Assets Disclosure [Text Block] Future estimated amortization expense Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] Earnings Per Share Earnings Per Share [Text Block] Schedule of Short-term Debt [Table] Schedule of Short-term Debt [Table] Short-term Debt [Line Items] Short-term Debt [Line Items] debt call premium debt call premium debt call premium Gains (Losses) on Extinguishment of Debt Investment shares sold Investment shares sold Investment shares sold Gain (Loss) on Sale of Investments Sale of Stock, Percentage of Ownership after Transaction Subsidiary or Equity Method Investee, Cumulative Percentage Ownership after All Transactions Investment Owned, at Cost Investment Owned, at Cost Statement of Comprehensive Income [Abstract] Other comprehensive income, net of tax Other Comprehensive Income (Loss), Net of Tax [Abstract] Reclassification adjustment for gains included in investment income Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Tax Investment securities, net Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, Net of Tax Defined benefit plans, income tax benefit (expense) Defined benefit plans, net Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Loss on Cash Flow Hedge Ineffectiveness Loss on Cash Flow Hedge Ineffectiveness Other Comprehensive Income (Loss), Reclassification Adjustment on Derivatives Included in Net Income, before Tax Derivative instruments, income tax benefit (expense) Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax Derivative instruments, net Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Net of Tax Reclassification adjustment for loss included in net income Other Comprehensive Income (Loss), Foreign Currency Translation Adjustment, Tax Foreign currency translation, net Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, Net of Tax Comprehensive income Comprehensive Income (Loss), Net of Tax, Including Portion Attributable to Noncontrolling Interest Less: comprehensive income attributable to redeemable non-controlling interest Comprehensive Income (Loss), Net of Tax, Attributable to Noncontrolling Interest Comprehensive income attributable to CME Group Comprehensive Income (Loss), Net of Tax, Attributable to Parent Fair Value Measurements Fair Value Disclosures [Text Block] Investment Type [Axis] Investment Type [Axis] Investments [Domain] Investments [Domain] Repurchase Agreements [Member] Repurchase Agreements [Member] Cash and Cash Equivalents, Fair Value Disclosure Cash and Cash Equivalents, Fair Value Disclosure Average Daily Clearing Settlement Average Daily Clearing Settlement Average Daily Clearing Settlement Remainder of 2015 Finite-Lived Intangible Assets, Amortization Expense, Remainder of Fiscal Year 2016 Finite-Lived Intangible Assets, Amortization Expense, Next Twelve Months 2017 Finite-Lived Intangible Assets, Amortization Expense, Year Two 2018 Finite-Lived Intangible Assets, Amortization Expense, Year Three 2019 Finite-Lived Intangible Assets, Amortization Expense, Year Four 2020 Finite-Lived Intangible Assets, Amortization Expense, Year Five Thereafter Finite-Lived Intangible Assets, Amortization Expense, after Year Five Document and Entity Information [Abstract] Document and Entity Information [Abstract] Class B Common Stock, Class B-1 [Member] Class B Common Stock, Class B1 [member] Class B Common Stock, Class B1 [Member] Class B Common Stock, Class B-2 [Member] Class B Common Stock, Class B2 [member] Class B Common Stock, Class B2 [Member] Class B Common Stock, Class B-3 [Member] Class B Common Stock, Class B3 [Member] Class B Common Stock, Class B3 [Member] Class B Common Stock, Class B-4 [Member] Class B Common Stock, Class B4 [member] Class B Common Stock, Class B4 [Member] Document Type Document Type Amendment Flag Amendment Flag Document Period End Date Document Period End Date Document Fiscal Period Focus Document Fiscal Period Focus Document Fiscal Year Focus Document Fiscal Year Focus 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 Entity Common Stock, Shares Outstanding Entity Common Stock, Shares Outstanding Debt Debt Disclosure [Text Block] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Schedule of Share-based Compensation Arrangements by Share-based Payment Award [Table] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Basic (in shares) Weighted Average Number of Shares Outstanding, Basic Dilutive Securities, Effect on EPS Incremental Common Shares Attributable to Dilutive Effect of Share-based Payment Arrangements Diluted (in shares) Weighted Average Number of Shares Outstanding, Diluted Earnings per common share, basic (in dollars per share) Earnings Per Share, Basic Earnings per common share, diluted (in dollars per share) Earnings Per Share, Diluted Income Statement [Abstract] Revenues Revenues [Abstract] Clearing and transaction fees Clearing Fees Revenue Market data and information services Market Data Revenue Access and communication fees Access and communication fees Revenue from providing access fees to customers for the use of electronic trading platform and revenue from telecommunication networks and communication services. Other Other Revenue, Net Total Revenues Revenues Expenses Costs and Expenses [Abstract] Compensation and benefits Labor and Related Expense Communications Communication Technology support services Information Technology and Data Processing Professional fees and outside services Professional Fees Occupancy and building operations Occupancy, Net Licensing and other fee agreements License Costs Other Other Cost and Expense, Operating Total Expenses Costs and Expenses Operating Income Operating Income (Loss) Non-Operating Income (Expense) Nonoperating Income (Expense) [Abstract] Investment income Investment Income, Nonoperating Gain (Loss) on Derivative Instruments, Net, Pretax Gain (Loss) on Derivative Instruments, Net, Pretax Interest and other borrowing costs Interest and Debt Expense Equity in net losses of unconsolidated subsidiaries Income (Loss) from Equity Method Investments Other non-operating income (expense) Other Nonoperating Income (Expense) Total Non-Operating Nonoperating Income (Expense) Income before Income Taxes Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Income tax provision Income Tax Expense (Benefit) Net income Net Income Attributable to CME Group Earnings per Common Share Attributable to CME Group: Basic (in dollars per share) Diluted (in dollars per share) Weighted Average Number of Common Shares: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Diluted (in shares)