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benefit (expense) Other Comprehensive Income (Loss), Derivatives Qualifying as Hedges, Tax Derivative Investments [Member] Accumulated Net Gain (Loss) from Cash Flow Hedges Attributable to Parent [Member] Schedule of Long-term Debt Instruments [Table Text Block] Schedule of Long-term Debt Instruments [Table Text Block] Depreciation and amortization Depreciation Entity Address, Street Address Entity Address, Address Line One Class B Common Stock, Class B-2 [Member] Class B Common Stock, Class B2 [member] Class B Common Stock, Class B2 [Member] Other assets Increase (Decrease) in Other Operating Assets Entity Emerging Growth Company Entity Emerging Growth Company Exercise of stock options Stock Issued During Period, Value, Stock Options Exercised Total intangible assets - other, net Indefinite-lived Intangible Assets (Excluding Goodwill) Schedule of Finite-Lived Intangible Assets [Table] Schedule of Finite-Lived Intangible Assets [Table] Deferred income taxes Deferred Income Tax Expense (Benefit) Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Line Items] Accumulated amortization Finite-Lived Intangible Assets, Accumulated Amortization Preferred stock, shares authorized (in shares) Preferred Stock, Shares Authorized Noncontrolling Interest [Member] Noncontrolling Interest [Member] Net realized and unrealized (gains) on investments Gain (Loss) on Investments Financial instruments measured at fair value on a recurring basis Fair Value Measurement and Measurement Inputs, Recurring and Nonrecurring [Text Block] Retained Earnings [Member] Retained Earnings [Member] Preferred stock, shares outstanding (in shares) Preferred Stock, Shares Outstanding Class B Common Stock, Class B-1 [Member] Class B Common Stock, Class B1 [member] Class B Common Stock, Class B1 [Member] Foreign Exchange [Member] Foreign Exchange [Member] CBOT CBOT [Member] CBOT Net Cash Used in Investing Activities Net Cash Provided by (Used in) Investing Activities Lessee, Operating Lease, Renewal Term Operating Lease Renewal Term Operating Lease Renewal Term Investments [Domain] Investments [Domain] Corporate Debt Securities [Member] Corporate Debt Securities [Member] Trading symbol Trading Symbol Goodwill, Other Increase (Decrease) Goodwill, Other Increase (Decrease) Contingent liability to SGX, amount of irrevocable letters of credit Guarantee Collateral Guarantee Collateral Earnings Per Share Earnings Per Share [Text Block] Organization, Consolidation and Presentation of Financial Statements [Abstract] Organization, Consolidation and Presentation of Financial Statements [Abstract] Entity Shell Company Entity Shell Company Fair Value, Recurring [Member] Fair Value, Recurring [Member] Guarantor Obligations [Line Items] Guarantor Obligations [Line Items] 2023 Finance Lease, Liability, to be Paid, Year Two Nonrecurring fair value [Abstract] Nonrecurring fair value [Abstract] Nonrecurring fair value [Abstract] Statement of Financial Position [Abstract] Statement of Financial Position [Abstract]