Condensed Consolidating Financial Statements - Statement of Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2017	Sep. 30, 2016	Sep. 30, 2017	Sep. 30, 2016
Condensed Income Statements, Captions [Line Items]
Revenue	$ 1,513	$ 1,439	$ 4,475	$ 4,262
Expenses:
Operating-related expenses	421	431	1,282	1,352
Selling and general expenses	388	337	1,077	986
Depreciation	22	22	61	63
Amortization of intangibles	24	23	73	71
Total expenses	855	813	2,493	2,472
Gain on disposition	0	(722)	0	(722)
Operating profit	658	1,348	1,982	2,512
Interest expense (income), net	37	39	110	122
Non-operating intercompany transactions	0	0	0	0
Income before taxes on income	621	1,309	1,872	2,390
(Benefit) provision for taxes on income	169	386	533	731
Equity in net income of subsidiaries	0	0	0	0
Net income	452	923	1,339	1,659
Less: net income attributable to noncontrolling interests	(38)	(31)	(105)	(90)
Net income attributable to S&P Global Inc.	414	892	1,234	1,569
Comprehensive income	473	915	1,434	1,624
Eliminations
Condensed Income Statements, Captions [Line Items]
Revenue	(35)	(33)	(102)	(95)
Expenses:
Operating-related expenses	(35)	(33)	(102)	(95)
Selling and general expenses	0	0	0	0
Depreciation	0	0	0	0
Amortization of intangibles	0	0	0	0
Total expenses	(35)	(33)	(102)	(95)
Gain on disposition		0		0
Operating profit	0	0	0	0
Interest expense (income), net	0	0	0	0
Non-operating intercompany transactions	13	48	1,502	552
Income before taxes on income	(13)	(48)	(1,502)	(552)
(Benefit) provision for taxes on income	0	0	0	0
Equity in net income of subsidiaries	(409)	(533)	(2,697)	(2,085)
Net income	(422)	(581)	(4,199)	(2,637)
Less: net income attributable to noncontrolling interests	(38)	(31)	(105)	(90)
Net income attributable to S&P Global Inc.	(460)	(612)	(4,304)	(2,727)
Comprehensive income	(427)	(561)	(4,199)	(2,636)
S&P Global Inc.
Condensed Income Statements, Captions [Line Items]
Revenue	184	175	545	516
Expenses:
Operating-related expenses	8	20	78	67
Selling and general expenses	62	52	108	106
Depreciation	9	8	23	28
Amortization of intangibles	0	0	0	0
Total expenses	79	80	209	201
Gain on disposition		(705)		(705)
Operating profit	105	800	336	1,020
Interest expense (income), net	41	43	119	129
Non-operating intercompany transactions	91	14	270	249
Income before taxes on income	(27)	743	(53)	642
(Benefit) provision for taxes on income	(45)	184	(91)	166
Equity in net income of subsidiaries	409	457	2,697	1,865
Net income	427	1,016	2,735	2,341
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to S&P Global Inc.	427	1,016	2,735	2,341
Comprehensive income	405	1,069	2,724	2,351
Standard & Poor's Financial Services LLC
Condensed Income Statements, Captions [Line Items]
Revenue	435	383	1,320	1,138
Expenses:
Operating-related expenses	124	111	359	342
Selling and general expenses	101	49	273	145
Depreciation	3	2	9	7
Amortization of intangibles	0	0	0	0
Total expenses	228	162	641	494
Gain on disposition		0		0
Operating profit	207	221	679	644
Interest expense (income), net	0	0	0	0
Non-operating intercompany transactions	(13)	(21)	(55)	(62)
Income before taxes on income	220	242	734	706
(Benefit) provision for taxes on income	107	95	325	263
Equity in net income of subsidiaries	0	76	0	220
Net income	113	223	409	663
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to S&P Global Inc.	113	223	409	663
Comprehensive income	113	216	409	662
Non-Guarantor Subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenue	929	914	2,712	2,703
Expenses:
Operating-related expenses	324	333	947	1,038
Selling and general expenses	225	236	696	735
Depreciation	10	12	29	28
Amortization of intangibles	24	23	73	71
Total expenses	583	604	1,745	1,872
Gain on disposition		(17)		(17)
Operating profit	346	327	967	848
Interest expense (income), net	(4)	(4)	(9)	(7)
Non-operating intercompany transactions	(91)	(41)	(1,717)	(739)
Income before taxes on income	441	372	2,693	1,594
(Benefit) provision for taxes on income	107	107	299	302
Equity in net income of subsidiaries	0	0	0	0
Net income	334	265	2,394	1,292
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to S&P Global Inc.	334	265	2,394	1,292
Comprehensive income	$ 382	$ 191	$ 2,500	$ 1,247