Restructuring - Summary (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Restructuring Plan, 2019
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	$ 25
Ending Reserve Balance	18
Restructuring Plan, 2018
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded		$ 25
Ending Reserve Balance	2
Ratings
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	11	8	$ 25
Market Intelligence
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	6		7
Platts
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	1		2
Operating segments | Ratings | Restructuring Plan, 2019
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	11
Ending Reserve Balance	7
Operating segments | Ratings | Restructuring Plan, 2018
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded		8
Ending Reserve Balance	0
Operating segments | Market Intelligence | Restructuring Plan, 2019
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	6
Ending Reserve Balance	5
Operating segments | Market Intelligence | Restructuring Plan, 2018
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded		7
Ending Reserve Balance	1
Operating segments | Platts | Restructuring Plan, 2019
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	1
Ending Reserve Balance	0
Operating segments | Platts | Restructuring Plan, 2018
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded		0
Ending Reserve Balance	0
Corporate
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	7	10	$ 10
Corporate | Restructuring Plan, 2019
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	7
Ending Reserve Balance	6
Corporate | Restructuring Plan, 2018
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded		$ 10
Ending Reserve Balance	$ 1