Consolidated Statements of Equity - USD ($) $ in Millions		Total	Total SPGI Equity	Common Stock $1 par	Additional Paid-in Capital	Retained Income	Accumulated Other Comprehensive Loss	Less: Treasury Stock	Noncontrolling Interests
Beginning Balance at Dec. 31, 2017		$ 766	$ 709	$ 412	$ 525	$ 10,023	$ (649)	$ (9,602)	$ 57
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	[1]	1,867	1,855			1,958	(103)		12
Dividends (Dividend declared per common share)		(514)	(503)			(503)			(11)
Share repurchases		(1,660)	(1,660)		(75)			1,585
Retirement of common stock		0		(118)				(118)
Employee stock plans		84	84		56			(28)
Change in redemption value of redeemable noncontrolling interest		(228)	(228)			(228)
Increase in CRISIL ownership		(23)	(25)		(25)				2
Stock consideration for Kensho		352	352		352
Other		40	44			34	10		(4)
Ending Balance at Dec. 31, 2018		684	628	294	833	11,284	(742)	(11,041)	56
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	[1]	2,251	2,241			2,123	118		10
Dividends (Dividend declared per common share)		(570)	(560)			(560)			(10)
Share repurchases		(1,240)	(1,240)		75			1,315
Employee stock plans		52	52		(5)			(57)
Capital contribution from noncontrolling interest		(36)	(36)			(36)
Change in redemption value of redeemable noncontrolling interest		(608)	(608)			(608)
Other		3	2			2			1
Ending Balance at Dec. 31, 2019		536	479	294	903	12,205	(624)	(12,299)	57
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	[1]	2,340	2,326			2,339	(13)		14
Dividends (Dividend declared per common share)		(656)	(645)			(645)			(11)
Share repurchases		(1,164)	(1,164)					1,164
Employee stock plans		45	45		43			(2)
Change in redemption value of redeemable noncontrolling interest		(532)	(532)			(532)
Other		2							2
Ending Balance at Dec. 31, 2020		$ 571	$ 509	$ 294	$ 946	$ 13,367	$ (637)	$ (13,461)	$ 62

[1] Excludes $181 million, $170 million and $151 million in 2020, 2019 and 2018, respectively, attributable to redeemable noncontrolling interest.