Restructuring (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Restructuring Plan, 2016
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	$ 30
Ending Reserve Balance	23
Restructuring Plan, 2015
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	63	$ 63
Ending Reserve Balance	10
Operating segments | Ratings
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	6	13	$ 45
Operating segments | Ratings | Restructuring Plan, 2016
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	14
Ending Reserve Balance	10
Operating segments | Ratings | Restructuring Plan, 2015
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded		18
Ending Reserve Balance	2
Operating segments | Market and Commodities Intelligence
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded		33	$ 25
Operating segments | Market and Commodities Intelligence | Restructuring Plan, 2016
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	10
Ending Reserve Balance	8
Operating segments | Market and Commodities Intelligence | Restructuring Plan, 2015
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded		34
Ending Reserve Balance	4
Operating segments | Indices | Restructuring Plan, 2016
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	1
Ending Reserve Balance	1
Operating segments | Indices | Restructuring Plan, 2015
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded		0
Ending Reserve Balance	0
Corporate | Restructuring Plan, 2016
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	5
Ending Reserve Balance	4
Corporate | Restructuring Plan, 2015
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded		$ 11
Ending Reserve Balance	$ 4