Restructuring (Details) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2017 USD ($)	Jun. 30, 2016 USD ($)	Jun. 30, 2017 USD ($) position	Jun. 30, 2016 USD ($)	Dec. 31, 2016 USD ($)
Ratings
Restructuring Cost and Reserve [Line Items]
Employee termination charges		$ 6		$ 6
Market and Commodities Intelligence
Restructuring Cost and Reserve [Line Items]
Employee termination charges	$ 5		$ 5
2017 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Workforce reduction (in positions) | position			120
Initial Charge Recorded			$ 5
Employee termination charges			5
Reduction of reserve			1
Ending Reserve Balance	4		4
Reserve balance	4		4
2017 Restructuring Plan | Ratings
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded			0
Ending Reserve Balance	0		0
Reserve balance	0		0
2017 Restructuring Plan | Market and Commodities Intelligence
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded			5
Ending Reserve Balance	4		4
Reserve balance	4		4
2017 Restructuring Plan | Indices
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded			0
Ending Reserve Balance	0		0
Reserve balance	0		0
2017 Restructuring Plan | Corporate
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded			0
Ending Reserve Balance	0		0
Reserve balance	0		$ 0
2016 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Workforce reduction (in positions) | position			230
Initial Charge Recorded			$ 30
Ending Reserve Balance	14		14
Reserve balance	14		14		$ 23
Restructuring charges paid			9
2016 Restructuring Plan | Ratings
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded			14
Ending Reserve Balance	7		7
Reserve balance	7		7
2016 Restructuring Plan | Market and Commodities Intelligence
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded			10
Ending Reserve Balance	4		4
Reserve balance	4		4
2016 Restructuring Plan | Indices
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded			1
Ending Reserve Balance	0		0
Reserve balance	0		0
2016 Restructuring Plan | Corporate
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded			5
Ending Reserve Balance	3		3
Reserve balance	$ 3		$ 3