Segment Reporting - Schedule of Segment Reporting Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment Reporting Information [Line Items]
Total revenues									$ 8,244	$ 6,547	$ 6,276
Transaction-based expenses									2,208	1,345	1,297
Total revenues, less transaction-based expenses	$ 1,671	$ 1,411	$ 1,395	$ 1,559	$ 1,298	$ 1,336	$ 1,298	$ 1,270	6,036	5,202	4,979
Operating expenses									3,003	2,529	2,396
Operating income	$ 780	$ 627	$ 744	$ 882	$ 622	$ 706	$ 680	$ 665	3,033	2,673	2,583
Exchanges
Segment Reporting Information [Line Items]
Total revenues									5,839	4,652	4,573
Transaction-based expenses									2,208	1,345	1,297
Total revenues, less transaction-based expenses									3,631	3,307	3,276
Operating expenses									1,242	1,140	1,114
Operating income									2,389	2,167	2,162
Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									1,810	1,756	1,681
Transaction-based expenses									0	0	0
Total revenues, less transaction-based expenses									1,810	1,756	1,681
Operating expenses									1,318	1,317	1,265
Operating income									492	439	416
Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									595	139	22
Transaction-based expenses									0	0	0
Total revenues, less transaction-based expenses									595	139	22
Operating expenses									443	72	17
Operating income									152	67	5
Energy futures and options
Segment Reporting Information [Line Items]
Total revenues									1,120	992	965
Energy futures and options | Exchanges
Segment Reporting Information [Line Items]
Total revenues									1,120	992	965
Energy futures and options | Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Energy futures and options | Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Agricultural and metals futures and options
Segment Reporting Information [Line Items]
Total revenues									245	251	251
Agricultural and metals futures and options | Exchanges
Segment Reporting Information [Line Items]
Total revenues									245	251	251
Agricultural and metals futures and options | Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Agricultural and metals futures and options | Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Financial futures and options
Segment Reporting Information [Line Items]
Total revenues									357	332	354
Financial futures and options | Exchanges
Segment Reporting Information [Line Items]
Total revenues									357	332	354
Financial futures and options | Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Financial futures and options | Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Cash equities and equity options
Segment Reporting Information [Line Items]
Total revenues									2,585	1,643	1,624
Cash equities and equity options | Exchanges
Segment Reporting Information [Line Items]
Total revenues									2,585	1,643	1,624
Cash equities and equity options | Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Cash equities and equity options | Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									0	0	0
OTC and other
Segment Reporting Information [Line Items]
Total revenues									296	233	227
OTC and other | Exchanges
Segment Reporting Information [Line Items]
Total revenues									296	233	227
OTC and other | Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									0	0	0
OTC and other | Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Data and connectivity services
Segment Reporting Information [Line Items]
Total revenues									790	752	708
Data and connectivity services | Exchanges
Segment Reporting Information [Line Items]
Total revenues									790	752	708
Data and connectivity services | Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Data and connectivity services | Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Listings
Segment Reporting Information [Line Items]
Total revenues									446	449	444
Listings | Exchanges
Segment Reporting Information [Line Items]
Total revenues									446	449	444
Listings | Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Listings | Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Fixed income execution
Segment Reporting Information [Line Items]
Total revenues									70	83	63
Fixed income execution | Exchanges
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Fixed income execution | Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									70	83	63
Fixed income execution | Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									0	0	0
CDS clearing
Segment Reporting Information [Line Items]
Total revenues									208	214	211
CDS clearing | Exchanges
Segment Reporting Information [Line Items]
Total revenues									0	0	0
CDS clearing | Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									208	214	211
CDS clearing | Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Fixed income data and analytics
Segment Reporting Information [Line Items]
Total revenues									1,018	969	931
Fixed income data and analytics | Exchanges
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Fixed income data and analytics | Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									1,018	969	931
Fixed income data and analytics | Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Other data and network services
Segment Reporting Information [Line Items]
Total revenues									514	490	476
Other data and network services | Exchanges
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Other data and network services | Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									514	490	476
Other data and network services | Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Origination technology
Segment Reporting Information [Line Items]
Total revenues									253	0	0
Origination technology | Exchanges
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Origination technology | Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Origination technology | Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									253	0	0
Network and closing solutions
Segment Reporting Information [Line Items]
Total revenues									158	36	0
Network and closing solutions | Exchanges
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Network and closing solutions | Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Network and closing solutions | Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									158	36	0
Data and analytics
Segment Reporting Information [Line Items]
Total revenues									22	0	0
Data and analytics | Exchanges
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Data and analytics | Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Data and analytics | Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									22	0	0
Registrations and other
Segment Reporting Information [Line Items]
Total revenues									162	103	22
Registrations and other | Exchanges
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Registrations and other | Fixed Income and Data Services
Segment Reporting Information [Line Items]
Total revenues									0	0	0
Registrations and other | Mortgage Technology
Segment Reporting Information [Line Items]
Total revenues									$ 162	$ 103	$ 22