Revenue Recognition - Narrative (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
Interest rates and other financial futures and options contracts
Disaggregation of Revenue [Line Items]
Total revenues	1,207	907	2,571	1,769
Trading and Clearing Segment
Disaggregation of Revenue [Line Items]
Total revenues	1,281	970	2,720	1,896
Trading and Clearing Segment | Interest rates and other financial futures and options contracts
Disaggregation of Revenue [Line Items]
Total revenues	1,207	907	2,571	1,769
Trading and Clearing Segment | Interest rates and other financial futures and options contracts | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenues	$ 64	$ 62	$ 153	$ 122