Earnings per Share - Summary (Details) - USD ($) $ / shares in Units, $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Amount attributable to S&P Global Inc. common shareholders:
Net income	$ 3,024	$ 2,339	$ 2,123
Basic weighted-average number of common shares outstanding (shares)	240,800,000	241,000,000.0	245,400,000
Effect of stock options and other dilutive securities (shares)	1,000,000.0	1,100,000	1,500,000
Diluted weighted-average number of common shares outstanding (shares)	241,800,000	242,100,000	246,900,000
Net income:
Basic (USD per share)	$ 12.56	$ 9.71	$ 8.65
Diluted (USD per share)	$ 12.51	$ 9.66	$ 8.60
Stock Options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of diluted EPS (shares)	0	0	0
Restricted performance shares
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of diluted EPS (shares)	500,000	400,000	400,000