Consolidated Statements of Income - USD ($) shares in Millions, $ in Millions	3 Months Ended		12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Income Statement [Abstract]
Revenue	$ 1,536	$ 1,589	$ 6,258	$ 6,063	$ 5,661
Expenses:
Operating-related expenses			1,701	1,695	1,773
Selling and general expenses			1,561	1,605	1,467
Depreciation			84	82	85
Amortization of intangibles			122	98	96
Total expenses			3,468	3,480	3,421
Gain on dispositions			0	0	(1,101)
Operating profit	704	627	2,790	2,583	3,341
Other income, net			(25)	(27)	(28)
Interest expense, net			134	149	181
Income before taxes on income			2,681	2,461	3,188
Provision for taxes on income			560	823	960
Net income	551	299	2,121	1,638	2,228
Less: net income attributable to noncontrolling interests			(163)	(142)	(122)
Net income attributable to S&P Global Inc.	$ 512	$ 263	$ 1,958	$ 1,496	$ 2,106
Net income:
Basic (USD per share)	$ 2.06	$ 1.03	$ 7.80	$ 5.84	$ 8.02
Diluted (USD per share)	$ 2.03	$ 1.02	$ 7.73	$ 5.78	$ 7.94
Weighted-average number of common shares outstanding:
Basic (shares)			250.9	256.3	262.8
Diluted (shares)			253.2	258.9	265.2
Actual shares outstanding at year end (shares)	248.4	253.7	248.4	253.7	258.3
Dividend declared per common share (USD per share)			$ 2	$ 1.64	$ 1.44