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Number of Shareholders Commencing Punitive Derivative Action

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

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Commitments and Contingencies (Details) $ in Millions	3 Months Ended	6 Months Ended
Commitments and Contingencies (Details) $ in Millions	Jun. 30, 2017 USD ($) lawsuit	Jun. 30, 2017 USD ($) lawsuit	Jan. 31, 2016 employee	Aug. 31, 2015 shareholder
Financial Crisis Litigation
Loss Contingencies [Line Items]
Number of lawsuits \| lawsuit	7	7
Shareholder Derivative Action
Loss Contingencies [Line Items]
Number of shareholders commencing punitive derivative action \| shareholder				2
CME Group \| S&P DJ Indices
Loss Contingencies [Line Items]
Revenues earned under license agreement \| $	$ 20	$ 38
Noncontrolling interest ownership by noncontrolling owners (as a percent)	27.00%	27.00%
S&P Global Ratings \| Shareholder Derivative Action
Loss Contingencies [Line Items]
Number of former employees named as defendants \| employee			9