Revenue Recognition - Schedule of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,966	$ 1,634	$ 4,081	$ 3,217
Transaction-based expenses	571	336	1,127	649
Total revenues, less transaction-based expenses	1,395	1,298	2,954	2,568
Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	621	547	1,387	1,075
Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	774	751	1,567	1,493
Trading and Clearing Segment
Disaggregation of Revenue [Line Items]
Total revenues	1,281	970	2,720	1,896
Transaction-based expenses	571	336	1,127	649
Total revenues, less transaction-based expenses	710	634	1,593	1,247
Trading and Clearing Segment | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	621	547	1,387	1,075
Trading and Clearing Segment | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	89	87	206	172
Data and Listings Segment
Disaggregation of Revenue [Line Items]
Total revenues	685	664	1,361	1,321
Transaction-based expenses	0	0	0	0
Total revenues, less transaction-based expenses	685	664	1,361	1,321
Data and Listings Segment | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	0	0	0	0
Data and Listings Segment | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	685	664	1,361	1,321
Transaction and clearing, net
Disaggregation of Revenue [Line Items]
Total revenues	1,207	907	2,571	1,769
Transaction and clearing, net | Trading and Clearing Segment
Disaggregation of Revenue [Line Items]
Total revenues	1,207	907	2,571	1,769
Transaction and clearing, net | Trading and Clearing Segment | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	64	62	153	122
Transaction and clearing, net | Data and Listings Segment
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Data services
Disaggregation of Revenue [Line Items]
Total revenues	574	553	1,138	1,099
Data services | Trading and Clearing Segment
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Data services | Data and Listings Segment
Disaggregation of Revenue [Line Items]
Total revenues	574	553	1,138	1,099
Listings
Disaggregation of Revenue [Line Items]
Total revenues	111	111	223	222
Listings | Trading and Clearing Segment
Disaggregation of Revenue [Line Items]
Total revenues	0	0	0	0
Listings | Data and Listings Segment
Disaggregation of Revenue [Line Items]
Total revenues	111	111	223	222
Other revenues
Disaggregation of Revenue [Line Items]
Total revenues	74	63	149	127
Other revenues | Trading and Clearing Segment
Disaggregation of Revenue [Line Items]
Total revenues	74	63	149	127
Other revenues | Data and Listings Segment
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0	$ 0	$ 0