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, 2014		$ 539	$ 488	$ 412	$ 493	$ 6,946	$ (514)	$ 6,849	$ 51
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	[1]	1,081	1,070			1,156	(86)		11
Dividends		(368)	(359)			(359)			(9)
Share repurchases		(1,002)	(1,000)					1,000	(2)
Employee stock plans		102	102		(18)			(120)
Change in redemption value of redeemable noncontrolling interest		(107)	(107)			(107)
Other		(2)	0						(2)
Ending Balance at Dec. 31, 2015		243	194	412	475	7,636	(600)	7,729	49
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	[1]	1,946	1,933			2,106	(173)		13
Dividends		(390)	(380)			(380)			(10)
Share repurchases		(1,097)	(1,097)					1,097
Employee stock plans		152	152		27			(125)
Change in redemption value of redeemable noncontrolling interest		(153)	(153)			(153)
Other		0	1			1			(1)
Ending Balance at Dec. 31, 2016		701	650	412	502	9,210	(773)	8,701	51
Increase (Decrease) in Stockholders' Equity [Roll Forward]
Comprehensive income	[1]	1,635	1,620			1,496	124		15
Dividends		(431)	(421)			(421)			(10)
Share repurchases		(1,006)	(1,001)					1,001	(5)
Employee stock plans		131	123		23			(100)	8
Change in redemption value of redeemable noncontrolling interest		(260)	(260)			(260)
Other		(2)	0						(2)
Ending Balance at Dec. 31, 2017		$ 768	$ 711	$ 412	$ 525	$ 10,025	$ (649)	$ 9,602	$ 57

[1] Excludes $127 million, $109 million and $101 million in 2017, 2016 and 2015, respectively, attributable to redeemable noncontrolling interest.