Revenue Recognition - Revenue Related to Investor Relations Performance Obligations Recognized (Details) - Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction, Start Date [Axis]: 2019-10-01	9 Months Ended
	Sep. 30, 2019
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	2 years
Revenue, period of customer revenue list recognized for NYSE	9 years
Revenue, period of customer revenue list recognized for NYSE area and NYSE American	5 years
Revenue, period of customer revenue list recognized for NYSE, modifications	6 years
Revenue, period of customer revenue list recognized for NYSE area and NYSE American, modifications	3 years
Interest rates and other financial futures and options contracts | Transferred over Time | Trading and Clearing Segment
Revenue, Remaining Performance Obligation, Expected Timing of Satisfaction [Line Items]
Revenue, remaining performance obligation, expected timing of satisfaction, period	1 month