Restructuring (Details) - 2015 Restructuring Plan $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2016 USD ($)	Dec. 31, 2015 USD ($) position
Restructuring Cost and Reserve [Line Items]
Workforce reduction (in positions) | position		550
Initial Charge Recorded	$ 63
Ending Reserve Balance	42	$ 50
Restructuring charges paid	8
S&P Ratings
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	18
Ending Reserve Balance	13
S&P Global Market Intelligence
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	31
Ending Reserve Balance	19
C&C
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	3
Ending Reserve Balance	1
Corporate
Restructuring Cost and Reserve [Line Items]
Initial Charge Recorded	11
Ending Reserve Balance	$ 9