Deferred Revenue (Changes in Deferred Revenue) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2021 USD ($)
Change in Contract with Customer Liability [Roll Forward]
Beginning balance	$ 306
Deferred revenue billed in the current period, net of recognition	403
Revenue recognized that was included in the beginning of the period	(102)
Foreign currency translation adjustment	(6)
Ending balance	601
Initial Listing Revenues
Change in Contract with Customer Liability [Roll Forward]
Beginning balance	91
Deferred revenue billed in the current period, net of recognition	37
Revenue recognized that was included in the beginning of the period	(17)
Foreign currency translation adjustment	(1)
Ending balance	110
Annual Listings Revenues
Change in Contract with Customer Liability [Roll Forward]
Beginning balance	2
Deferred revenue billed in the current period, net of recognition	221
Revenue recognized that was included in the beginning of the period	(1)
Foreign currency translation adjustment	(1)
Ending balance	221
IR & ESG Services Revenues
Change in Contract with Customer Liability [Roll Forward]
Beginning balance	46
Deferred revenue billed in the current period, net of recognition	28
Revenue recognized that was included in the beginning of the period	(22)
Foreign currency translation adjustment	0
Ending balance	52
Investment Intelligence Revenues
Change in Contract with Customer Liability [Roll Forward]
Beginning balance	97
Deferred revenue billed in the current period, net of recognition	50
Revenue recognized that was included in the beginning of the period	(33)
Foreign currency translation adjustment	0
Ending balance	114
Market Technology Revenues
Change in Contract with Customer Liability [Roll Forward]
Beginning balance	53
Deferred revenue billed in the current period, net of recognition	57
Revenue recognized that was included in the beginning of the period	(23)
Foreign currency translation adjustment	(3)
Ending balance	84
Other
Change in Contract with Customer Liability [Roll Forward]
Beginning balance	17
Deferred revenue billed in the current period, net of recognition	10
Revenue recognized that was included in the beginning of the period	(6)
Foreign currency translation adjustment	(1)
Ending balance	$ 20