Earnings Per Share (Details) - USD ($) $ / shares in Units, shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2016	Jun. 30, 2015	Jun. 30, 2016	Jun. 30, 2015
Amounts attributable to S&P Global Inc. common shareholders:
Net income	$ 383	$ 353	$ 677	$ 656
Basic weighted-average number of common shares outstanding (in shares)	264.5	273.1	264.7	273.3
Effect of stock options and other dilutive securities (in shares)	2.2	2.6	2.3	2.7
Diluted weighted-average number of common shares outstanding (in shares)	266.7	275.7	267.0	276.0
Earnings per share attributable to S&P Global Inc. common shareholders:
Basic (in dollars per share)	$ 1.45	$ 1.29	$ 2.56	$ 2.40
Diluted (in dollars per share)	$ 1.44	$ 1.28	$ 2.54	$ 2.38
Restricted performance shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding shares not included in the computation of diluted earnings per share (in shares)			1.2	1.7