Restructuring - Summary (Details) - 2020 Restructuring Plan - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2021	Dec. 31, 2020
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	$ 65
Ending Reserve Balance	17	$ 58
Operating Segments | Ratings
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	4
Ending Reserve Balance	1
Operating Segments | Market Intelligence
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	27
Ending Reserve Balance	6
Operating Segments | Platts
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	10
Ending Reserve Balance	4
Operating Segments | Indices
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	5
Ending Reserve Balance	1
Corporate
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	19
Ending Reserve Balance	$ 5