Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Income Statement [Abstract]
Revenue	$ 1,609	$ 1,509	$ 3,176	$ 2,962
Expenses:
Operating-related expenses	446	432	884	843
Selling and general expenses	439	364	812	725
Depreciation	19	20	40	39
Amortization of intangibles	33	25	57	49
Total expenses	937	841	1,793	1,656
Operating profit	672	668	1,383	1,306
Other income, net	(11)	(9)	(16)	(18)
Interest expense, net	26	37	61	74
Income before taxes on income	657	640	1,338	1,250
Provision for taxes on income	156	183	303	363
Net income	501	457	1,035	887
Less: net income attributable to noncontrolling interests	(40)	(36)	(84)	(67)
Net income attributable to S&P Global Inc.	$ 461	$ 421	$ 951	$ 820
Net income:
Basic (USD per share)	$ 1.83	$ 1.63	$ 3.78	$ 3.18
Diluted (USD per share)	$ 1.82	$ 1.62	$ 3.75	$ 3.15
Weighted-average number of common shares outstanding:
Basic (shares)	251.1	257.3	251.7	257.7
Diluted (shares)	253.3	259.9	253.8	260.4
Actual shares outstanding at period end (shares)			251.4	257.0
Dividend declared per common share (USD per share)	$ 0.5	$ 0.41	$ 1	$ 0.82