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Asset Categories [Axis] Plan Asset Categories [Domain] Plan Asset Categories [Domain] Money Market Funds [Member] Money Market Funds [Member] Fixed Income Securities [Member] Fixed Income Securities [Member] US Equity [Member] US Equity [Member] US Equity [Member] Foreign Equity [Member] Foreign Equity Mutual Fund [Member] Foreign Equity Mutual Fund [Member] Commodity [Member] Commodity [Member] Statement [Line Items] Statement [Line Items] Defined Benefit Plan, Fair Value of Plan Assets Defined Benefit Plan, Fair Value of Plan Assets General Discussion of Derivative Instruments and Hedging Activities [Abstract] Derivative Instruments Derivative Instruments and Hedging Activities Disclosure [Text Block] Statement, Scenario [Axis] Scenario [Axis] Scenario, Unspecified [Domain] Scenario, Unspecified [Domain] 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 Securities, Net Gain (Loss) on Sale of Securities, Net Gains (Losses) on Extinguishment of Debt Gains (Losses) on Extinguishment of Debt Gain (Loss) on Sale of Property Plant Equipment Gain (Loss) on Disposition of Property Plant Equipment 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 assets and liabilities: 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 tax 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, net Payments to 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tax benefits related to employee option exercises and restricted stock vesting Excess Tax Benefit from Share-based Compensation, Financing Activities Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability Business Combination, Contingent Consideration Arrangements, Change in Amount of Contingent Consideration, Liability Other Proceeds from (Payments for) Other Financing Activities Net Cash Provided by (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 (excluding securities lending program) Interest Paid Non-cash financing activities: Cash Flow Noncash Financing Activities Disclosure Abstract Cash Flow, Noncash Financing Activities Disclosure [Abstract] dividends declared dividends declared dividends declared Income Tax Disclosure [Abstract] Income Taxes Income Tax Disclosure [Text Block] Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Defined Benefit Plan, Change in Benefit Obligation [Roll Forward] Balance at January 1 Defined Benefit Plan, Benefit Obligation Service cost Defined Benefit Plan, Service Cost Interest cost Defined Benefit Plan, Interest Cost Actuarial (gain) loss Defined Benefit Plan, Actuarial Gain (Loss) Benefits paid Defined Benefit Plan, Benefits Paid Balance at December 31 Temporary Equity [Abstract] Changes in redeemable non-controlling interest Redeemable Noncontrolling Interest [Table Text Block] Income before income taxes: Domestic Income (Loss) from Continuing Operations before Income Taxes, Domestic Income before income taxes: Foreign Income (Loss) from Continuing Operations before Income Taxes, Foreign Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Current income tax provision: Federal Current Federal Tax Expense (Benefit) Current income tax provision: State Current State and Local Tax Expense (Benefit) Current income tax provision: Foreign Current Foreign Tax Expense (Benefit) Current income tax provision: Total Current Income Tax Expense (Benefit) Deferred income tax provision: Federal Deferred Federal Income Tax Expense (Benefit) Deferred income tax provision: State Deferred State and Local Income Tax Expense (Benefit) Deferred income tax provision: Foreign Deferred Foreign Income Tax Expense (Benefit) Deferred income tax provision: Total Total Income Tax Provision Income Tax Expense (Benefit) 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] Goodwill and Intangible Assets Disclosure [Abstract] Goodwill by Segment [Axis] Segments [Axis] Goodwill, Segment [Domain] Segments [Domain] CBOT holdings [Member] CBOT Holdings [Member] CBOT Holdings [Member] NYMEX holdings [Member] NYMEX Holdings [Member] NYMEX Holdings [Member] Other Affiliates [Member] Other Affiliates [Member] Total Goodwill, beginning balance Goodwill Business Combinations Goodwill, Acquired During Period Goodwill, Transfers Goodwill, Transfers Goodwill, Written off Related to Sale of Business Unit Goodwill, Written off Related to Sale of Business Unit Other Activity Goodwill, Translation and Purchase Accounting Adjustments Total Goodwill, ending balance Legal Entity [Axis] Legal Entity [Axis] Entity [Domain] Entity [Domain] BM&F [Member] BM& FBOVESPA SA [Member] BM&FBOVESPA SA [Member] Operating Loss 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Property Class [Axis] Major Property Class [Domain] Major Property Class [Domain] First Lease Renewal Option [Member] First Lease Renewal Option [Member] First Lease Renewal Option [Member] Second Lease Renewal Option [Member] Second Lease Renewal Option [Member] Second Lease Renewal Option [Member] Property Subject to or Available for Operating Lease [Axis] Property Subject to or Available for Operating Lease [Axis] Property Subject to or Available for Operating Lease [Domain] Property Subject to or Available for Operating Lease [Domain] NYMEX [Member] NYMEX [Member] NYMEX [Member] Chicago CBOT Building [Member] [Member] Chicago CBOT Building [Member] [Member] Chicago CBOT Building [Member] [Member] Chicago [Member] Chicago [Member] Chicago [Member] Additional Office Space Chicago [Member] Additional Office Space Chicago [Member] Additional Office Space Chicago [Member] Operating leases number of renewal options Operating Leases Number Of Renewal Options Operating leases number of renewal options Lessee Leasing Arrangements, Operating Leases, Renewal Term Lessee Leasing Arrangements, Operating Leases, Renewal Term Operating leases, rent expense Operating Leases, Rent Expense Performance Bonds and Guaranty Fund Contributions [Abstract] Performance Bonds and Guaranty Fund Contributions [Abstract] Restricted Cash and Cash Equivalents, Cash and Cash Equivalents [Axis] Restricted Cash and Cash Equivalents [Axis] Cash and Cash Equivalents [Domain] Cash and Cash Equivalents [Domain] Cash [Member] Cash [Member] Non-Cash Deposits and IEF Funds [Member] Securities and IEF Funds [Member] Securities and IEF Funds [Member] Performance bonds Performance bonds Performance bonds Guaranty Fund Contributions Guaranty Fund Contributions Guaranty Fund Contributions Cross-margin arrangements Cross-margin arrangements Cross-margin arrangements Performance collateral for delivery Performance collateral for delivery Performance collateral for delivery Total Good Faith and Margin Deposits with Broker-Dealers Statement of Stockholders' Equity [Abstract] Class of Stock [Axis] Class of Stock [Axis] Class of Stock [Domain] Class of Stock [Domain] Series A junior participating preferred stock [Member] Series A Preferred Stock [Member] Class A Common Stock (Shares) [Member] Common Class A [Member] Class B Common Stock (Shares) [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] Increase (Decrease) in Stockholders' Equity [Roll Forward] Increase (Decrease) in Stockholders' Equity [Roll Forward] Beginning Balance (in shares) Common Stock, Shares, Outstanding Total Equity Beginning Balance Stockholders' Equity, Including Portion Attributable to Noncontrolling Interest Comprehensive income: Comprehensive Income (Loss), Net of Tax, Attributable to Parent [Abstract] Net income attributable to CME Group Net Income (Loss) Attributable to Parent Net Income (Loss) Attributable to Noncontrolling Interest Net Income (Loss) Attributable to Nonredeemable Noncontrolling Interest Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Net Income (Loss), Including Portion Attributable to Nonredeemable Noncontrolling Interest Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Other Comprehensive Income (Loss), Net of Tax, Portion Attributable to Parent Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, Net of Tax Total comprehensive income attributable to CME Group Comprehensive Income (Loss), Net of Tax, Attributable to Parent Dividends, Cash Dividends, Cash Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests Noncontrolling Interest, Decrease from Redemptions or Purchase of Interests 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, Gross Stock Issued During Period, Shares, Restricted Stock Award, Gross Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Stock Issued During Period, Value, Restricted Stock Award, Net of Forfeitures Shares issued to Board of Directors (in shares) Stock Issued During Period, Shares, Issued for Services Stock Issued to Board of Directors, Value, Issued for Services Stock Issued During Period, Value, Issued for Services Shares issued under Employee Stock Purchase Plan (in shares) Stock Issued During Period, Shares, Employee Stock Purchase Plans Shares issued under Employee Stock Purchase Plan Stock Issued During Period, Value, Employee Stock Purchase Plan Stock-based compensation Stock Granted, Value, Share-based Compensation, Net of Forfeitures Ending Balance (in shares) Total Equity Ending Balance Accumulated Defined Benefit Plans Adjustment [Member] Accumulated Defined Benefit Plans Adjustment Attributable to Parent [Member] Accumulated Net Unrealized Investment Gain (Loss) [Member] Accumulated Net Investment Gain (Loss) Attributable to Parent [Member] Accumulated Net Gain (Loss) from Designated or Qualifying Cash Flow Hedges [Member] Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] Foreign Currency Gain (Loss) [Member] Foreign Currency Gain (Loss) [Member] Accumulated Other Comprehensive Income [Roll Forward] Accumulated Other Comprehensive Income [Roll Forward] Accumulated Other Comprehensive Income [Roll Forward] Stockholders' Equity Attributable to Parent, beginning Stockholders' Equity Attributable to Parent Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax Other Comprehensive Income (Loss), Unrealized Holding Gain (Loss) on Securities Arising During Period, before Tax Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Adjustment, before Tax Other comprehensive income before reclassifications and income tax benefit (expense) Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Adjustment, before Tax Other Comprehensive Income (Loss), Reclassification, Pension and Other Postretirement Benefit Plans, Net Gain (Loss) Recognized in Net Periodic Benefit Cost, before Tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI, Pension and Other Postretirement Benefit Plans, for Net Gain (Loss), before Tax Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax Other Comprehensive Income (Loss), Unrealized Gain (Loss) on Derivatives Arising During Period, before Tax Comprehensive Income Before Reclassification Adjustments Other Comprehensive Income (Loss), before Reclassifications, before Tax Other Comprehensive Income (Loss), Reclassification Adjustment for Sale of Securities Included in Net Income, before Tax Other Comprehensive Income (Loss), Reclassification Adjustment from AOCI for Sale of Securities, 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), Foreign Currency Transaction and Translation Reclassification Adjustment Realized upon Sale or Liquidation, before Tax Other Comprehensive Income (Loss), Foreign Currency Transaction and Translation Reclassification Adjustment from AOCI, Realized upon Sale or Liquidation, before Tax Comprehensive Income Reclassification Adjustments Reclassification from Accumulated Other Comprehensive Income, Current Period, 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 Other Comprehensive Income (Loss), Pension and Other Postretirement Benefit Plans, Tax 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 Other Comprehensive Income (Loss), Net of Tax Other Comprehensive Income (Loss), Tax Other Comprehensive Income (Loss), Net of Tax Other Comprehensive Income (Loss), Net of Tax Stockholders' Equity Attributable to Parent, ending Long-term Investments [Abstract] Long-term Investments Equity Method Investments and Joint Ventures Disclosure [Text Block] Summary of the change in projected benefit obligation Schedule of Changes in Projected Benefit Obligations [Table Text Block] Change in plan assets Schedule of Changes in Fair Value of Plan Assets [Table Text Block] Fair value of plan assets Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block] Components of net pension expenses and the assumptions used to determine the end-of-year projected benefit obligation and net pension expense in aggregate Schedule of Net Benefit Costs [Table Text Block] Asset allocation for the plan Schedule of Allocation of Plan Assets [Table Text Block] Prior service costs and actuarial losses included in accumulated other comprehensive income (loss) Schedule of Amounts Recognized in Other Comprehensive Income (Loss) [Table Text Block] Anticipated benefit payments from the plan in future years Schedule of Expected Benefit Payments [Table Text Block] Debt [Abstract] Debt [Abstract] Seven Hundred Fifty Million Fixed Rate Notes Due March Two Thousand Twenty Two, Interest Equal To Four Point Three Zero Percent [Member] Seven Hundred Fifty Million Fixed Rate Notes Due March Two Thousand Twenty Two, Interest Equal To Four Point Three Zero Percent [Member] Seven Hundred Fifty Million Fixed Rate Notes Due March Two Thousand Twenty Two, Interest Equal To Four Point Three Zero Percent [Member] $750.0 million fixed rates notes due September 2043, stated rate of 5.30% Seven Hundred Fifty Million Fixed Rate Notes Due March Two Thousand Twenty Five, Interest Equal To Three Point Zero Percent [Member] [Member] Seven Hundred Fifty Million Fixed Rate Notes Due March Two Thousand Twenty Five, Interest Equal To Four Point Three Zero Percent [Member] [Member] $750.0 million fixed rate notes due March 2025, stated rate of 3.00% 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 Long-term Debt Long-term Debt, Current and Noncurrent [Abstract] 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, maturity date Debt Instrument, Maturity Date Debt Instrument, Interest Rate, Stated Percentage Debt Instrument, Interest Rate, Stated Percentage Valuation and Qualifying Accounts [Abstract] Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Schedule of Valuation and Qualifying Accounts Disclosure [Text Block] Quarterly Financial Data [Abstract] Quarterly Information Quarterly Financial Information [Text Block] Schedule of future minimum payments under non-cancelable operating leases Schedule of Future Minimum Rental Payments for Operating Leases [Table Text Block] Schedule of other commitments Contractual Obligation, Fiscal Year Maturity Schedule [Table Text Block] Investment Type [Axis] Investment Type [Axis] Investment Type [Domain] Investments [Domain] U.S. Treasury Performance Bond [Member] U.S. Treasury Performance Bond [Member] U.S. Treasury Performance Bond [Member] Guaranty Fund [Axis] Guaranty Fund [Axis] Guaranty Fund [Axis] Guaranty Fund [Domain] Guaranty Fund [Domain] [Domain] for Guaranty Fund [Axis] CME Base Guaranty Fund [Member] CME Base Guaranty Fund [Member] CME Base Guaranty Fund [Member] CME IRS Guaranty Fund [Member] [Member] CME IRS Guaranty Fund [Member] [Member] CME IRS Guaranty Fund [Member] [Member] CME CDS Guaranty Fund [Member] [Member] CME CDS Guaranty Fund [Member] [Member] CME CDS Guaranty Fund [Member] [Member] CMECE Commodity Fund [Member] CMECE Commodity Fund [Member] CMECE Commodity Fund [Member] CMECE Interest Rate Swap [Member] CMECE Interest Rate Swap [Member] CMECE Interest Rate Swap [Member] Line of Credit Facility [Axis] Lender Name [Axis] Line of Credit Facility, Lender [Domain] Line of Credit Facility, Lender [Domain] 364-day fully secured, committed line of credit Line of Credit Facility, Fully Secured Committed [Member] Line of Credit Facility, Fully Secured Committed [Member] Revolving senior credit facility Letter of Credit Facility, Revolving Senior Credit Facility [Member] Letter of Credit Facility, Revolving Senior Credit Facility [Member] Available-for-sale Securities, Amortized Cost Basis Available-for-sale Securities, Amortized Cost Basis Average daily clearing settlement Average Daily Clearing Settlement Average Daily Clearing Settlement Available-for-sale Securities Available-for-sale Securities Total principal in IEF programs Total principal in IEF programs Total principal in IEF programs Management fees earned under the IEF programs I E F Revenue I E F Revenue Percentage share of cross-margining collateral Percentage Share of Cross-margining Collateral Percentage Share of Cross-margining Collateral Corporate Contribution Corporate Contribution Corporate Contribution Minimum Corporate Contribution Minimum Corporate Contribution Minimum Corporate Contribution Working capital designated for clearance of default in over the counter credit default swap, percent Working Capital Percent For Over the Counter Credit Default Swap, Percent Working Capital Percent For Over the Counter Credit Default Swap, Percent Working capital designated for clearance of default in over the counter interest rate swap Working Capital For Over the Counter Interest Rate Swap Working Capital For Over the Counter Interest Rate Swap Line of Credit Facility, Maximum Borrowing Capacity Line of Credit Facility, Maximum Borrowing Capacity Line of Credit, Guaranty Fund Collateral Available Line of Credit, Guaranty Fund Collateral Available Line of Credit, Guaranty Fund Collateral Available Option on increase in line of credit Line of Credit Facility, Option to Increase, Maximum Borrowing Capacity Line of Credit Facility, Option to Increase, Maximum Borrowing Capacity Days fully secured Committed Line Of Credit Number Of Days Fully Secured Committed Line Of Credit Number Of Days Fully Secured Intraday settlements of cash performance bonds Intraday settlements of 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Award Date [Domain] Award Type [Axis] Award Type [Axis] Equity Award [Domain] Equity Award [Domain] Range [Axis] Range [Axis] Range [Domain] Range [Domain] Vesting [Axis] Vesting [Axis] Vesting [Domain] Vesting [Domain] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Share-based Compensation Arrangement by Share-based Payment Award [Line Items] Compensation expense Allocated Share-based Compensation Expense Income tax benefit recognized Employee Service Share-based Compensation, Tax Benefit from Compensation Expense Contingencies Schedule of Loss Contingencies by Contingency [Table Text Block] Bolsa Mexicana De Valores, S A B De C V [Member] Bolsa Mexicana De Valores, S A B De C V [Member] Bolsa Mexicana De Valores, S A B De C V Bursa Malaysia Derivatives Berhad [Member] Bursa Malaysia Derivatives Berhad [Member] Bursa Malaysia Derivatives Berhad [Member] DME Holdings [Member] DME Holdings [Member] DME Holdings [Member] S&P/DJI [Member] SandPDJI [Member] SandPDJI [Member] Equity Method Investment, Ownership Percentage Equity Method Investment, Ownership Percentage Fair value of investment Investment Owned, at Fair Value Cost-basis value of investment Investment Owned, at Cost 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 Gains (losses) on derivative investments Gain (Loss) on Derivative Instruments, Net, Pretax Interest and other borrowing costs Interest and Debt Expense Equity in net (gains) losses of unconsolidated subsidiaries Income (Loss) from Equity Method Investments Other income (expense) Other Nonoperating Income (Expense) Total Non-Operating Nonoperating Income (Expense) Income (Loss) from Continuing Operations before Income Taxes, Extraordinary Items, Noncontrolling Interest Income tax provision Net Income Net Income (Loss) Attributable to Noncontrolling Interest Net Income (Loss) Attributable to Noncontrolling Interest Net Income Attributable to CME Group Earnings per Common Share Attributable to CME Group: Earnings Per Share [Abstract] Basic Earnings Per Share, Basic Diluted Earnings Per Share, Diluted Weighted Average Number of Common Shares: Weighted Average Number of Shares Outstanding, Diluted [Abstract] Basic Weighted Average Number of Shares Outstanding, Basic Diluted Weighted Average Number of Shares Outstanding, Diluted Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization and Business Organization, Consolidation and Presentation of Financial Statements Disclosure [Text Block] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding in Shares [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding in Shares [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding in Shares [Roll Forward] Number of shares outstanding at December 31 (shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number Number of shares exercised Number of shares cancelled Share-based Compensation Arrangement by Share-based Payment Award, Options, Expirations in Period Number of shares outstanding at December 31 (shares) Number of shares exercisable at December 31 (shares) Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Number Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding [Roll Forward] Weighted average exercise price outstanding, beginning Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Exercise Price Weighted average exercise price exercised Share-based Compensation Arrangements by Share-based Payment Award, Options, Exercises in Period, Weighted Average Exercise Price Weighted average exercise price cancelled Share-based Compensation Arrangements by Share-based Payment Award, Options, Expirations in Period, Weighted Average Exercise Price Weighted average exercise price outstanding, ending Weighted average exercise price exercisable Share-based Compensation Arrangement by Share-based Payment Award, Options, Exercisable, Weighted Average Exercise Price Weighted average remaining contractual life outstanding Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Weighted Average Remaining Contractual Term Share-based Compensation Arrangement by Share-based Payment Award, Options, Vested and Expected to Vest, Exercisable, Weighted Average 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Benefit Plans Pension and Other Postretirement Benefits Disclosure [Text Block] Quarterly Information Schedule of Quarterly Financial Information [Table Text Block] Deferred Compensation Arrangement with Individual, Postretirement Benefits, by Type of Deferred Compensation [Axis] Other Postretirement Benefits, Individual Contracts, Type of Deferred Compensation [Axis] Type of Deferred Compensation [Domain] Other Postretirement Benefits, Individual Contracts, Type of Deferred Compensation [Domain] Other Postretirement Benefit Plan [Member] Other Postretirement Benefit Plan [Member] Age for participation eligibility in benefit plan Eligible Age To Participate In Benefit Plan Eligible age to participate in benefit plan Years of service for vesting eligibility Deferred Compensation Arrangement with Individual, Requisite Service Period Accumulated benefit obligation Defined Benefit Plan, Accumulated Benefit Obligation Excess of pension plan assets over the projected benefit obligation Defined Benefit Plan, Funded Status of Plan Defined Benefit Plan Funding Goal Percentage Defined Benefit Plan Funding Goal Percentage Defined Benefit Plan Funding Goal Percentage Estimated liabilities exceeding the fair value of the plan assets Pension Plans Benefit Obligation Liabilities Exceeded Fair Value Of Plan Assets Pension Plans Benefit Obligation Liabilities Exceeded Fair Value Of Plan Assets Estimated contribution to meet projected excess of pension plan liabilities of pension plan assets Defined Benefit Plans, Estimated Future Employer Contributions in Next Fiscal Year Amortization of actuarial loss from accumulated other comprehensive income (loss) into net periodic benefit costs Defined Benefit Plan, Amount to be Amortized from Accumulated Other Comprehensive Income (Loss) Next Fiscal Year Percentage of employees base salary matched by employer, maximum Defined Contribution Plan, Employer Matching Contribution, Percent of Employees' Gross Pay Defined Contribution Plan, Cost Recognized Defined Contribution Plan, Cost Recognized Total contribution Total Contribution Total Contribution Total obligation Total Obligation Total Obligation Fair value of assets Fair Value Of Assets Under Retirement Plan Fair Value Of Assets Under NYMEX Members Retirement Plan And Benefits Operating Leases, Future Minimum Payments Due [Abstract] Operating Leases, Future Minimum Payments Due, Fiscal Year Maturity [Abstract] 2016 Operating Leases, Future Minimum Payments Due, Next Twelve Months 2017 Operating Leases, Future Minimum Payments, Due in Two Years 2018 Operating Leases, Future Minimum Payments, Due in Three Years 2019 Operating Leases, Future Minimum Payments, Due in Four Years 2020 Operating Leases, Future Minimum Payments, Due in Five Years Thereafter Operating Leases, Future Minimum Payments, Due Thereafter Total Operating Leases, Future Minimum Payments Due Unrecorded Unconditional Purchase Obligation [Abstract] Unrecorded Unconditional Purchase Obligation, Fiscal Year Maturity [Abstract] 2016 Unrecorded Unconditional Purchase Obligation, Due in Next Twelve Months 2017 Unrecorded Unconditional Purchase Obligation, Due within Two Years 2018 Unrecorded Unconditional Purchase Obligation, Due within Three Years 2019 Unrecorded Unconditional Purchase Obligation, Due within Four Years 2020 Unrecorded Unconditional Purchase Obligation, Due within Five Years Thereafter Unrecorded Unconditional Purchase Obligation, Due after Five Years Total Unrecorded Unconditional Purchase Obligation, Total Unrecorded Unconditional Purchase Obligation, Total 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 Fair Value Disclosures [Text Block] Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Table] Fair Value Measurements, Recurring and Nonrecurring [Table] Financial Instrument [Axis] Financial Instrument [Axis] Financial Instruments [Domain] Financial Instruments [Domain] 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] Fair Value, Hierarchy [Axis] Fair Value, Measurements, Fair Value Hierarchy [Domain] Mutual funds [Member] Mutual funds [Member] Mutual Funds [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] Trading Securities at Fair Value Marketable Securities at Fair Value Investments, Fair Value Disclosure Investment Owned, at Fair Value Total Assets at Fair Value Assets, Fair Value Disclosure Derivative Liability Derivative Liability Business Combination, Contingent Consideration Liability Business Combination, Contingent Consideration, Liability Total liabilities at fair value Financial and Nonfinancial Liabilities, Fair Value Disclosure Business Acquisition [Axis] Business Acquisition [Axis] Business Acquisition, Acquiree [Domain] Business Acquisition, Acquiree [Domain] Net book value Stock-Based Payments Disclosure of Compensation Related Costs, Share-based Payments [Text Block] Marketable Securities Investments in Debt and Marketable Equity Securities (and Certain Trading Assets) Disclosure [Text Block] Minimum Defined Benefit Plan, Target Plan Asset Allocations Range Minimum Maximum Defined Benefit Plan, Target Plan Asset Allocations Range Maximum Noncontrolling Interest [Table] Noncontrolling Interest [Table] S&P/Dow Jones Indices LLC [Member] S&P/Dow Jones Indices LLC [Member] S&P/Dow Jones Indices LLC [Member] Dow Jones [Member] Dow Jones [Member] Dow Jones CME Group net of non-controlling interest [Member] CME Group net of non-controlling interest [Member] CME Group net of non-controlling interest [Member] Noncontrolling Interest [Line Items] Noncontrolling Interest [Line Items] Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Noncontrolling Interest, Ownership Percentage by Noncontrolling Owners Adjustments to Additional Paid in Capital, Deferred Tax Liabilities Adjustments to Additional Paid in Capital, Deferred Tax Liabilities Adjustments to Additional Paid in Capital, Deferred Tax Liabilities Gain on Purchase of NonControlling Interest Gain on Purchase of NonControlling Interest Gain on Purchase of NonControlling Interest Prior Service Cost Beginning Balance Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Prior Service Cost (Credit), before Tax Defined Benefit Plan, Amortization of Net Prior Service Cost (Credit) Other Comprehensive (Income) Loss, Pension and Other Postretirement Benefit Plans, Net Prior Service Cost (Credit) Arising During Period, before Tax Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Defined Benefit Plan, Amortization of Prior Service Cost (Credit) Prior Service Cost Ending Balance Actuarial Losses [Roll Forward] Actuarial Losses [Roll Forward] Actuarial Losses [Roll Forward] Actuarial Loss Beginning Balance Pension and Other Postretirement Benefit Plans, Accumulated Other Comprehensive Income (Loss), Net Gains (Losses), before Tax Actuarial Loss Ending Balance Class A Common Stock Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] 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] Business Combination, Contingent Consideration Liability, Beginning Included in operating expense Fair Value, Measurement with Unobservable Inputs Reconciliation, Recurring Basis, Liability, Gain (Loss) Included in Earnings Contingent Consideration Settlement Contingent Consideration Settlement Contingent Consideration Settlement Business Combination, Contingent Consideration Liability, Ending Comprehensive Income (Loss) Note [Text Block] Comprehensive Income (Loss) Note [Text Block] Principles of Consolidation Consolidation, Policy [Policy Text Block] Use of Estimates Use of Estimates, Policy [Policy Text Block] Cash and Cash Equivalents Cash and Cash Equivalents, Policy [Policy Text Block] Investment, Policy [Policy Text Block] Investment, Policy [Policy Text Block] Fair Value of Financial Instruments Fair Value of Financial Instruments, Policy [Policy Text Block] Derivative Investments Derivatives, Policy [Policy Text Block] Accounts Receivable Receivables, Policy [Policy Text Block] Performance Bonds and Guaranty Fund Contributions Performance Bonds And Security Deposit [Text Block] Performance Bonds And Security Deposit [Text Block] Property, Equipment and Leasehold Improvements Property, Plant and Equipment, Policy [Policy Text Block] Operating Leases Lease, Policy [Policy Text Block] Goodwill and Other Intangible Assets Goodwill and Intangible Assets, Policy [Policy Text Block] Business Combinations Business Combinations and Other Purchase of Business Transactions, Policy [Policy Text Block] Employee Benefit Plans Compensation Related Costs, Policy [Policy Text Block] Foreign Currency Translation Foreign Currency Transactions and Translations Policy [Policy Text Block] Revenue Recognition Revenue Recognition, Policy [Policy Text Block] Share-Based Payments Share-based Compensation, Option and Incentive Plans Policy [Policy Text Block] Marketing Costs Advertising Costs, Policy [Policy Text Block] Income Taxes Income Tax, Policy [Policy Text Block] Segment Reporting Segment Reporting Disclosure [Text Block]