Restructuring - Summary (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020	Dec. 31, 2020
Operating Segments | Market Intelligence
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded		$ 2
Corporate
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded		$ 7
2020 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	$ 65
Ending Reserve Balance	42		$ 58
2020 Restructuring Plan | Operating Segments | Ratings
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	4
Ending Reserve Balance	2
2020 Restructuring Plan | Operating Segments | Market Intelligence
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	27
Ending Reserve Balance	17
2020 Restructuring Plan | Operating Segments | Platts
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	10
Ending Reserve Balance	7
2020 Restructuring Plan | Operating Segments | Indices
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	5
Ending Reserve Balance	4
2020 Restructuring Plan | Corporate
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	19
Ending Reserve Balance	$ 12