Restructuring (Details) $ in Millions	9 Months Ended		12 Months Ended
	Sep. 30, 2016 USD ($) position	Sep. 30, 2015 USD ($)	Dec. 31, 2015 USD ($) position
S&P Global Ratings
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	$ 6	$ 8
S&P Global Market Intelligence
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded		12
S&P Global Platts
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded		$ 1
2016 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	17
Ending Reserve Balance	13
Restructuring charges paid	4
2016 Restructuring Plan | S&P Global Ratings
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	8
Ending Reserve Balance	5
2016 Restructuring Plan | S&P Global Market Intelligence
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	1
Ending Reserve Balance	1
2016 Restructuring Plan | S&P Global Platts
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	6
Ending Reserve Balance	5
2016 Restructuring Plan | Corporate
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	2
Ending Reserve Balance	$ 2
2015 Restructuring Plan
Restructuring Cost and Reserve [Line Items]
Workforce reduction (in positions) | position	100		550
Initial Charge Recorded	$ 63
Ending Reserve Balance	23		$ 50
Restructuring charges paid	27
2015 Restructuring Plan | S&P Global Ratings
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	18
Ending Reserve Balance	7
2015 Restructuring Plan | S&P Global Market Intelligence
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	31
Ending Reserve Balance	10
2015 Restructuring Plan | S&P Global Platts
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	3
Ending Reserve Balance	0
2015 Restructuring Plan | Corporate
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	11
Ending Reserve Balance	$ 6