Segment Reporting (Details) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019 USD ($)	Sep. 30, 2018 USD ($)	Sep. 30, 2019 USD ($) segment member	Sep. 30, 2018 USD ($) member
Segment Reporting Information [Line Items]
Number of reportable segments | segment			2
Revenues:
Total revenues	$ 1,663	$ 1,463	$ 4,880	$ 4,599
Transaction-based expenses	327	263	976	928
Total revenues, less transaction-based expenses	1,336	1,200	3,904	3,671
Operating expenses	630	598	1,853	1,764
Operating income	706	602	2,051	1,907
Trading and Clearing Segment
Revenues:
Total revenues	996	821	2,892	2,691
Transaction-based expenses	327	263	976	928
Total revenues, less transaction-based expenses	669	558	1,916	1,763
Operating expenses	255	230	732	655
Operating income	414	328	1,184	1,108
Data and Listings Segment
Revenues:
Total revenues	667	642	1,988	1,908
Transaction-based expenses	0	0	0	0
Total revenues, less transaction-based expenses	667	642	1,988	1,908
Operating expenses	375	368	1,121	1,109
Operating income	292	274	867	799
Sales Revenue, Net | Trading and Clearing Segment
Revenues:
Total revenues	$ 92	$ 89	$ 286	$ 300
Number of members | member			1	1
Concentration risk, percentage	14.00%	16.00%	15.00%	17.00%
Energy futures and options contracts
Revenues:
Total revenues	$ 265	$ 223	$ 749	$ 708
Energy futures and options contracts | Trading and Clearing Segment
Revenues:
Total revenues	265	223	749	708
Energy futures and options contracts | Data and Listings Segment
Revenues:
Total revenues	0	0	0	0
Agricultural and metals futures and options contracts
Revenues:
Total revenues	60	58	194	197
Agricultural and metals futures and options contracts | Trading and Clearing Segment
Revenues:
Total revenues	60	58	194	197
Agricultural and metals futures and options contracts | Data and Listings Segment
Revenues:
Total revenues	0	0	0	0
Financial futures and options contracts
Revenues:
Total revenues	91	77	252	262
Financial futures and options contracts | Trading and Clearing Segment
Revenues:
Total revenues	91	77	252	262
Financial futures and options contracts | Data and Listings Segment
Revenues:
Total revenues	0	0	0	0
Cash equities and equity options
Revenues:
Total revenues	401	335	1,201	1,162
Cash equities and equity options | Trading and Clearing Segment
Revenues:
Total revenues	401	335	1,201	1,162
Cash equities and equity options | Data and Listings Segment
Revenues:
Total revenues	0	0	0	0
Fixed income and credit
Revenues:
Total revenues	101	56	268	157
Fixed income and credit | Trading and Clearing Segment
Revenues:
Total revenues	101	56	268	157
Fixed income and credit | Data and Listings Segment
Revenues:
Total revenues	0	0	0	0
OTC and other transactions
Revenues:
Total revenues	11	11	34	36
OTC and other transactions | Trading and Clearing Segment
Revenues:
Total revenues	11	11	34	36
OTC and other transactions | Data and Listings Segment
Revenues:
Total revenues	0	0	0	0
Pricing and analytics
Revenues:
Total revenues	273	263	809	779
Pricing and analytics | Trading and Clearing Segment
Revenues:
Total revenues	0	0	0	0
Pricing and analytics | Data and Listings Segment
Revenues:
Total revenues	273	263	809	779
Exchange data and feeds
Revenues:
Total revenues	172	168	528	496
Exchange data and feeds | Trading and Clearing Segment
Revenues:
Total revenues	0	0	0	0
Exchange data and feeds | Data and Listings Segment
Revenues:
Total revenues	172	168	528	496
Desktops and connectivity
Revenues:
Total revenues	108	99	315	301
Desktops and connectivity | Trading and Clearing Segment
Revenues:
Total revenues	0	0	0	0
Desktops and connectivity | Data and Listings Segment
Revenues:
Total revenues	108	99	315	301
Listings
Revenues:
Total revenues	114	112	336	332
Listings | Trading and Clearing Segment
Revenues:
Total revenues	0	0	0	0
Listings | Data and Listings Segment
Revenues:
Total revenues	114	112	336	332
Other revenues
Revenues:
Total revenues	67	61	194	169
Other revenues | Trading and Clearing Segment
Revenues:
Total revenues	67	61	194	169
Other revenues | Data and Listings Segment
Revenues:
Total revenues	$ 0	$ 0	$ 0	$ 0