Consolidated Statements of Income (Unaudited) - USD ($) shares in Millions, $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2018	Sep. 30, 2017	Sep. 30, 2018	Sep. 30, 2017
Income Statement [Abstract]
Revenue	$ 1,546	$ 1,513	$ 4,721	$ 4,475
Expenses:
Operating-related expenses	406	419	1,290	1,262
Selling and general expenses	383	399	1,194	1,123
Depreciation	20	22	60	61
Amortization of intangibles	33	24	91	73
Total expenses	842	864	2,635	2,519
Operating profit	704	649	2,086	1,956
Other income, net	(6)	(9)	(22)	(26)
Interest expense, net	38	37	98	110
Income before taxes on income	672	621	2,010	1,872
Provision for taxes on income	137	169	440	533
Net income	535	452	1,570	1,339
Less: net income attributable to noncontrolling interests	(40)	(38)	(123)	(105)
Net income attributable to S&P Global Inc.	$ 495	$ 414	$ 1,447	$ 1,234
Net income:
Basic (USD per share)	$ 1.97	$ 1.62	$ 5.75	$ 4.80
Diluted (USD per share)	$ 1.95	$ 1.61	$ 5.70	$ 4.75
Weighted-average number of common shares outstanding:
Basic (shares)	251.3	255.5	251.6	257.0
Diluted (shares)	253.5	257.9	253.7	259.5
Actual shares outstanding at period end (shares)			250.9	255.0
Dividend declared per common share (USD per share)	$ 0.5	$ 0.41	$ 1.5	$ 1.23