Restructuring - Summary (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Dec. 31, 2019
2020 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	$ 9
Ending Reserve Balance	7
2019 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	25
Ending Reserve Balance	11	$ 18
Operating Segments | Market Intelligence
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	2
Operating Segments | 2020 Restructuring Plan | Ratings
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	0
Ending Reserve Balance	0
Operating Segments | 2020 Restructuring Plan | Market Intelligence
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	2
Ending Reserve Balance	1
Operating Segments | 2020 Restructuring Plan | Platts
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	0
Ending Reserve Balance	0
Operating Segments | 2019 Restructuring Plan | Ratings
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	11
Ending Reserve Balance	4
Operating Segments | 2019 Restructuring Plan | Market Intelligence
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	6
Ending Reserve Balance	4
Operating Segments | 2019 Restructuring Plan | Platts
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	1
Ending Reserve Balance	0
Corporate
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	7
Corporate | 2020 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	7
Ending Reserve Balance	6
Corporate | 2019 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	7
Ending Reserve Balance	$ 3