Goodwill and Other Intangible Assets - Schedule of Intangible Assets and Related Accumulated Amortization (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 5,530	$ 5,403
Less accumulated amortization	(1,811)	(1,532)
Total finite-lived intangible assets, net	3,719	3,871
Total other indefinite-lived intangible assets	6,539	6,591
Total other intangible assets, net	$ 10,258	10,462	$ 10,269
Useful Life (Years)	17 years 1 month 6 days
Exchange registrations, licenses and contracts with indefinite lives
Finite-Lived Intangible Assets [Line Items]
Total other indefinite-lived intangible assets	$ 6,228	6,253
Trade names and trademarks with indefinite lives
Finite-Lived Intangible Assets [Line Items]
Total other indefinite-lived intangible assets	280	280
In-process research and development
Finite-Lived Intangible Assets [Line Items]
Total other indefinite-lived intangible assets	23	49
Other
Finite-Lived Intangible Assets [Line Items]
Total other indefinite-lived intangible assets	8	9
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 4,510	4,406
Customer relationships | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)	3 years
Customer relationships | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)	25 years
Technology
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 544	524
Technology | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)	2 years 6 months
Technology | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)	11 years
Trading products with finite lives
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 237	237
Useful Life (Years)	20 years
Data/databases
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 150	150
Data/databases | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)	4 years
Data/databases | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)	10 years
Market data provider relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 11	11
Useful Life (Years)	20 years
Non-compete agreements
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 42	39
Non-compete agreements | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)	1 year
Non-compete agreements | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)	5 years
Other
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, gross	$ 36	$ 36
Other | Minimum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)	1 year
Other | Maximum
Finite-Lived Intangible Assets [Line Items]
Useful Life (Years)	5 years