Commitments and Contingencies - Narrative (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Loss Contingencies [Line Items]
Period of lease extension options	12 years
Period of options to terminate lease	1 year
Contribution to noncontrolling interest	$ 51	$ 18
CME Group \| S&P DJ Indices
Loss Contingencies [Line Items]
Revenues earned under license agreement	$ 47	$ 29
Minimum
Loss Contingencies [Line Items]
Remaining lease terms	1 year
Maximum
Loss Contingencies [Line Items]
Remaining lease terms	14 years
CME Group
Loss Contingencies [Line Items]
Noncontrolling interest ownership by noncontrolling owners (as a percent)	27.00%
CME Group \| S&P DJ Indices
Loss Contingencies [Line Items]
Noncontrolling interest ownership by noncontrolling owners (as a percent)	27.00%

Lessee, Operating Lease, Period of Options to Terminate Lease

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Lessee, Operating Lease, Remaining Lease Term

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Term of lessee's operating lease renewal, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents reported fact of one year, five months, and thirteen days.

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Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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The equity interest of noncontrolling shareholders, partners or other equity holders in consolidated entity.

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Amount of cash outflow to a noncontrolling interest. Includes, but not limited to, reduction of noncontrolling interest ownership. Excludes dividends paid to the noncontrolling interest.

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Amount of revenue, fees and commissions earned from transactions between (a) a parent company and its subsidiaries; (b) subsidiaries of a common parent; (c) an entity and trusts for the benefit of employees, for example, but not limited to, pension and profit-sharing trusts that are managed by or under the trusteeship of the entity's management; (d) an entity and its principal, owners, management, or members of their immediate families; and (e) affiliates.

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