Earnings Per Share - Schedule of calculation for basic and diluted earnings per share (Details) - USD ($) $ / shares in Units, $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Amounts attributable to S&P Global Inc. common shareholders:
Net income	$ 1,235	$ 755
Basic weighted-average number of common shares outstanding (shares)	275,200,000	240,600,000
Effect of stock options and other dilutive securities (shares)	1,100,000	1,000,000.0
Diluted weighted-average number of common shares outstanding (shares)	276,300,000	241,600,000
Earnings per share attributable to S&P Global Inc. common shareholders:
Basic (USD per share)	$ 4.49	$ 3.14
Diluted (USD per share)	$ 4.47	$ 3.12
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Net income	$ 1,235	$ 755
Stock options
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of diluted earnings (shares)	0	0
Restricted Stock and Unit Awards
Antidilutive Securities Excluded from Computation of Earnings Per Share [Line Items]
Antidilutive shares excluded from computation of diluted earnings (shares)	700,000	400,000