Revenue Recognition - Schedule of Revenue (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Disaggregation of Revenue [Line Items]
Total revenues	$ 1,930	$ 1,663	$ 6,011	$ 4,880
Transaction-based expenses	519	327	1,646	976
Total revenues, less transaction-based expenses	1,411	1,336	4,365	3,904
Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	595	578	1,982	1,653
Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	816	758	2,383	2,251
Trading and Clearing Segment
Disaggregation of Revenue [Line Items]
Total revenues	1,230	996	3,950	2,892
Transaction-based expenses	519	327	1,646	976
Total revenues, less transaction-based expenses	711	669	2,304	1,916
Trading and Clearing Segment | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	595	578	1,982	1,653
Trading and Clearing Segment | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenues, less transaction-based expenses	116	91	322	263
Data and Listings Segment
Disaggregation of Revenue [Line Items]
Total revenues	700	667	2,061	1,988
Transaction-based expenses	0	0	0	0
Total revenues, less transaction-based expenses	700	667	2,061	1,988
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	700	667	2,061	1,988
Transaction and clearing, net
Disaggregation of Revenue [Line Items]
Total revenues	1,155	929	3,726	2,698
Transaction and clearing, net | Trading and Clearing Segment
Disaggregation of Revenue [Line Items]
Total revenues	1,155	929	3,726	2,698
Transaction and clearing, net | Trading and Clearing Segment | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	57	66	209	188
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	589	553	1,727	1,652
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	589	553	1,727	1,652
Listings
Disaggregation of Revenue [Line Items]
Total revenues	111	114	334	336
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	114	334	336
Other revenues
Disaggregation of Revenue [Line Items]
Total revenues	75	67	224	194
Other revenues | Trading and Clearing Segment
Disaggregation of Revenue [Line Items]
Total revenues	75	67	224	194
Other revenues | Data and Listings Segment
Disaggregation of Revenue [Line Items]
Total revenues	$ 0	$ 0	$ 0	$ 0