Earnings (Loss) per Share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2015	Sep. 30, 2015	Jun. 30, 2015	Mar. 31, 2015	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014
Amount attributable to S&P Global Inc. common shareholders:
Income (loss) from continuing operations									$ 2,106	$ 1,156	$ (293)
Income from discontinued operations									0	0	178
Net income (loss) attributable to S&P Global Inc.	$ 537	$ 892	$ 383	$ 294	$ 248	$ 252	$ 353	$ 303	$ 2,106	$ 1,156	$ (115)
Basic weighted-average number of common shares outstanding (in shares)									262,800,000	271,600,000	271,500,000
Effect of stock options and other dilutive securities (in shares)									2,400,000	3,000,000	0
Diluted weighted-average number of common shares outstanding (in shares)									265,200,000	274,600,000	271,500,000
Income (loss) from continuing operations:
Basic (in dollars per share)									$ 8.02	$ 4.26	$ (1.08)
Diluted (in dollars per share)									7.94	4.21	(1.08)
Income from discontinued operations:
Basic (in dollars per share)									0.00	0.00	0.66
Diluted (in dollars per share)									0.00	0.00	0.66
Net income (loss):
Basic (in dollars per share)	$ 2.07	$ 3.39	$ 1.45	$ 1.11	$ 0.92	$ 0.93	$ 1.29	$ 1.11	8.02	4.26	(0.42)
Diluted (in dollars per share)	$ 2.05	$ 3.36	$ 1.44	$ 1.10	$ 0.91	$ 0.92	$ 1.28	$ 1.10	$ 7.94	$ 4.21	$ (0.42)
Employee Stock Option
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding shares not included in the computation of diluted earnings per share for both restricted stock and stock options (in shares)									0	0	2,900,000
Restricted Stock
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Outstanding shares not included in the computation of diluted earnings per share for both restricted stock and stock options (in shares)									700,000	900,000	3,200,000