Consolidated Statement 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
Balance at beginning of period at Dec. 31, 2017		$ 768		$ 711		$ 412	$ 525	$ 10,025	$ (649)	$ (9,602)	$ 57
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	[1]	1,394		1,383				1,447	(64)		11
Dividends		(388)		(379)				(379)			(9)
Share repurchases		(1,113)		(1,113)						1,113
Employee stock plans		56		56			45			(11)
Change in redemption value of redeemable noncontrolling interest		(119)		(119)				(119)
Increase in CRISIL ownership		(26)		(25)			(25)				(1)
Stock consideration for Kensho		352		352			352
Other	[2]	31		36				26	10		(5)
Balance at end of period at Sep. 30, 2018		955		902		412	897	11,000	(703)	(10,704)	53
Balance at beginning of period at Jun. 30, 2018		633		580		412	732	10,677	(705)	(10,536)	53
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income		500	[1]	497	[1]			495	2		3
Dividends		(128)		(126)				(126)			(2)
Share repurchases		(13)		(13)			150			163
Employee stock plans		10		10			15			5
Change in redemption value of redeemable noncontrolling interest		(46)		(46)				(46)
Other		(1)									(1)
Balance at end of period at Sep. 30, 2018		955		902		412	897	11,000	(703)	(10,704)	53
Balance at beginning of period at Dec. 31, 2018		684		628		294	833	11,284	(742)	(11,041)	56
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	[1]	1,647		1,640				1,582	58		7
Dividends		(427)		(420)				(420)			(7)
Share repurchases		(1,144)		(1,144)			(30)			1,174
Employee stock plans		34		34			(28)			(62)
Capital contribution from noncontrolling interest		(36)		(36)				(36)
Change in redemption value of redeemable noncontrolling interest		(356)		(356)				(356)
Balance at end of period at Sep. 30, 2019		402		346		294	835	12,054	(684)	(12,153)	56
Balance at beginning of period at Jun. 30, 2019		570		512		294	790	11,710	(651)	(11,631)	58
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income		584	[1]	583	[1]			617	(34)		1
Dividends		(140)		(139)				(139)			(1)
Share repurchases		(500)		(500)			30			530
Employee stock plans		23		23			15			(8)
Change in redemption value of redeemable noncontrolling interest		(134)		(134)				(134)
Other		(1)		1					1		(2)
Balance at end of period at Sep. 30, 2019		$ 402		$ 346		$ 294	$ 835	$ 12,054	$ (684)	$ (12,153)	$ 56

[1] Excludes comprehensive income of $44 million and $36 million for the three months ended September 30, 2019 and 2018, respectively, and $128 million and $112 million for the nine months ended September 30, 2019 and 2018, respectively, attributable to our redeemable noncontrolling interest.

[2] Reflects opening balance sheet adjustments related to the adoption of the new revenue recognition standard and the reclassification of the unrealized loss on investments from Accumulated other comprehensive loss to Retained income.