Segment Reporting (Details) $ in Millions	3 Months Ended
	Mar. 31, 2019 USD ($) segment member	Mar. 31, 2018 USD ($) member
Segment Reporting Information [Line Items]
Number of reportable segments | segment	2
Revenues:
Total revenues	$ 1,583	$ 1,580
Transaction-based expenses	313	355
Total revenues, less transaction-based expenses	1,270	1,225
Operating expenses	605	575
Operating income	665	650
Trading and Clearing Segment
Revenues:
Total revenues	926	951
Transaction-based expenses	313	355
Total revenues, less transaction-based expenses	613	596
Operating expenses	228	207
Operating income	385	389
Data and Listings Segment
Revenues:
Total revenues	657	629
Transaction-based expenses	0	0
Total revenues, less transaction-based expenses	657	629
Operating expenses	377	368
Operating income	280	261
Sales Revenue, Net | Trading and Clearing Segment
Revenues:
Total revenues	$ 95	$ 104
Number of members | member	1	1
Concentration risk, percentage	16.00%	18.00%
Energy futures and options contracts
Revenues:
Total revenues	$ 229	$ 235
Energy futures and options contracts | Trading and Clearing Segment
Revenues:
Total revenues	229	235
Energy futures and options contracts | Data and Listings Segment
Revenues:
Total revenues	0	0
Agricultural and metals futures and options contracts
Revenues:
Total revenues	62	65
Agricultural and metals futures and options contracts | Trading and Clearing Segment
Revenues:
Total revenues	62	65
Agricultural and metals futures and options contracts | Data and Listings Segment
Revenues:
Total revenues	0	0
Financial futures and options contracts
Revenues:
Total revenues	83	91
Financial futures and options contracts | Trading and Clearing Segment
Revenues:
Total revenues	83	91
Financial futures and options contracts | Data and Listings Segment
Revenues:
Total revenues	0	0
Cash equities and equity options
Revenues:
Total revenues	390	438
Cash equities and equity options | Trading and Clearing Segment
Revenues:
Total revenues	390	438
Cash equities and equity options | Data and Listings Segment
Revenues:
Total revenues	0	0
Fixed income and credit
Revenues:
Total revenues	87	56
Fixed income and credit | Trading and Clearing Segment
Revenues:
Total revenues	87	56
Fixed income and credit | Data and Listings Segment
Revenues:
Total revenues	0	0
OTC and other transactions
Revenues:
Total revenues	11	13
OTC and other transactions | Trading and Clearing Segment
Revenues:
Total revenues	11	13
OTC and other transactions | Data and Listings Segment
Revenues:
Total revenues	0	0
Pricing and analytics
Revenues:
Total revenues	266	254
Pricing and analytics | Trading and Clearing Segment
Revenues:
Total revenues	0	0
Pricing and analytics | Data and Listings Segment
Revenues:
Total revenues	266	254
Exchange data and feeds
Revenues:
Total revenues	176	164
Exchange data and feeds | Trading and Clearing Segment
Revenues:
Total revenues	0	0
Exchange data and feeds | Data and Listings Segment
Revenues:
Total revenues	176	164
Desktops and connectivity
Revenues:
Total revenues	104	102
Desktops and connectivity | Trading and Clearing Segment
Revenues:
Total revenues	0	0
Desktops and connectivity | Data and Listings Segment
Revenues:
Total revenues	104	102
Listings
Revenues:
Total revenues	111	109
Listings | Trading and Clearing Segment
Revenues:
Total revenues	0	0
Listings | Data and Listings Segment
Revenues:
Total revenues	111	109
Other revenues
Revenues:
Total revenues	64	53
Other revenues | Trading and Clearing Segment
Revenues:
Total revenues	64	53
Other revenues | Data and Listings Segment
Revenues:
Total revenues	$ 0	$ 0