Condensed Consolidating Financial Statements - Statement of Income (Details) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018
Condensed Income Statements, Captions [Line Items]
Revenue	$ 1,704	$ 1,609	$ 3,275	$ 3,176
Expenses:
Operating-related expenses	452	441	898	877
Selling and general expenses	387	444	755	819
Depreciation	21	19	41	40
Amortization of intangibles	31	33	63	57
Total expenses	891	937	1,757	1,793
Operating profit	813	672	1,518	1,383
Other expense (income), net	(6)	(11)	97	(16)
Interest expense (income), net	37	26	73	61
Non-operating intercompany transactions	0	0	0	0
Income before taxes on income	782	657	1,348	1,338
(Benefit) provision for taxes on income	180	156	293	303
Equity in net income of subsidiaries	0	0	0	0
Net income	602	501	1,055	1,035
Less: net income attributable to noncontrolling interests	(47)	(40)	(90)	(84)
Net income attributable to S&P Global Inc.	555	461	965	951
Comprehensive income	584	426	1,146	969
Eliminations
Condensed Income Statements, Captions [Line Items]
Revenue	(40)	(39)	(77)	(74)
Expenses:
Operating-related expenses	(40)	(39)	(77)	(74)
Selling and general expenses	0	0	0	0
Depreciation	0	0	0	0
Amortization of intangibles	0	0	0	0
Total expenses	(40)	(39)	(77)	(74)
Operating profit	0	0	0	0
Other expense (income), net	0	0	0	0
Interest expense (income), net	0	0	0	0
Non-operating intercompany transactions	1,159	294	1,182	1,311
Income before taxes on income	(1,159)	(294)	(1,182)	(1,311)
(Benefit) provision for taxes on income	0	0	0	0
Equity in net income of subsidiaries	(1,741)	(812)	(2,247)	(2,324)
Net income	(2,900)	(1,106)	(3,429)	(3,635)
Less: net income attributable to noncontrolling interests	(47)	(40)	(90)	(84)
Net income attributable to S&P Global Inc.	(2,947)	(1,146)	(3,519)	(3,719)
Comprehensive income	(2,900)	(1,103)	(3,430)	(3,635)
S&P Global Inc. | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Revenue	208	200	409	391
Expenses:
Operating-related expenses	46	43	85	74
Selling and general expenses	51	69	75	108
Depreciation	10	11	22	20
Amortization of intangibles	0	0	0	0
Total expenses	107	123	182	202
Operating profit	101	77	227	189
Other expense (income), net	(5)	(6)	102	(14)
Interest expense (income), net	40	28	77	66
Non-operating intercompany transactions	95	86	191	186
Income before taxes on income	(29)	(31)	(143)	(49)
(Benefit) provision for taxes on income	(3)	27	(43)	13
Equity in net income of subsidiaries	1,741	812	2,247	2,324
Net income	1,715	754	2,147	2,262
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to S&P Global Inc.	1,715	754	2,147	2,262
Comprehensive income	1,721	764	2,235	2,251
Standard & Poor's Financial Services LLC | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Revenue	489	463	925	897
Expenses:
Operating-related expenses	110	107	228	224
Selling and general expenses	83	57	163	143
Depreciation	4	2	6	4
Amortization of intangibles	0	0	0	0
Total expenses	197	166	397	371
Operating profit	292	297	528	526
Other expense (income), net	0	0	0	0
Interest expense (income), net	0	0	0	1
Non-operating intercompany transactions	(20)	(22)	(37)	(43)
Income before taxes on income	312	319	565	568
(Benefit) provision for taxes on income	89	75	159	146
Equity in net income of subsidiaries	0	0	0	0
Net income	223	244	406	422
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to S&P Global Inc.	223	244	406	422
Comprehensive income	223	244	406	421
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Revenue	1,047	985	2,018	1,962
Expenses:
Operating-related expenses	336	330	662	653
Selling and general expenses	253	318	517	568
Depreciation	7	6	13	16
Amortization of intangibles	31	33	63	57
Total expenses	627	687	1,255	1,294
Operating profit	420	298	763	668
Other expense (income), net	(1)	(5)	(5)	(2)
Interest expense (income), net	(3)	(2)	(4)	(6)
Non-operating intercompany transactions	(1,234)	(358)	(1,336)	(1,454)
Income before taxes on income	1,658	663	2,108	2,130
(Benefit) provision for taxes on income	94	54	177	144
Equity in net income of subsidiaries	0	0	0	0
Net income	1,564	609	1,931	1,986
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to S&P Global Inc.	1,564	609	1,931	1,986
Comprehensive income	$ 1,540	$ 521	$ 1,935	$ 1,932