Revenue Recognition - Schedule of Revenue (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,583	$ 1,580
Transaction-based expenses	313	355
Total revenues, less transaction-based expenses	1,270	1,225
Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	528	509
Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	742	716
Trading and Clearing Segment
Disaggregation of Revenue [Line Items]
Total revenues	926	951
Transaction-based expenses	313	355
Total revenues, less transaction-based expenses	613	596
Trading and Clearing Segment | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	528	509
Trading and Clearing Segment | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	85	87
Data and Listings Segment
Disaggregation of Revenue [Line Items]
Total revenues	657	629
Transaction-based expenses	0	0
Total revenues, less transaction-based expenses	657	629
Data and Listings Segment | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	0	0
Data and Listings Segment | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	657	629
Transaction and clearing, net
Disaggregation of Revenue [Line Items]
Total revenues	862	898
Transaction and clearing, net | Trading and Clearing Segment
Disaggregation of Revenue [Line Items]
Total revenues	862	898
Transaction and clearing, net | Trading and Clearing Segment | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	60	63
Transaction and clearing, net | Data and Listings Segment
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Data services
Disaggregation of Revenue [Line Items]
Total revenues	546	520
Data services | Trading and Clearing Segment
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Data services | Data and Listings Segment
Disaggregation of Revenue [Line Items]
Total revenues	546	520
Listings
Disaggregation of Revenue [Line Items]
Total revenues	111	109
Listings | Trading and Clearing Segment
Disaggregation of Revenue [Line Items]
Total revenues	0	0
Listings | Data and Listings Segment
Disaggregation of Revenue [Line Items]
Total revenues	111	109
Other revenues
Disaggregation of Revenue [Line Items]
Total revenues	64	53
Other revenues | Trading and Clearing Segment
Disaggregation of Revenue [Line Items]
Total revenues	64	53
Other revenues | Data and Listings Segment
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0