Condensed Consolidating Financial Statements - Statement of Income (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018
Condensed Income Statements, Captions [Line Items]
Revenue	$ 1,689	$ 1,546	$ 4,964	$ 4,721
Expenses:
Operating-related expenses	438	410	1,337	1,287
Selling and general expenses	360	379	1,115	1,197
Depreciation	20	20	61	60
Amortization of intangibles	29	33	92	91
Total expenses	847	842	2,605	2,635
Gain on dispositions	(49)	0	(49)	0
Operating profit	891	704	2,408	2,086
Other expense, net	8	(6)	104	(22)
Interest expense (income), net	32	38	105	98
Non-operating intercompany transactions	0	0	0	0
Income before taxes on income	851	672	2,199	2,010
Provision for taxes on income	189	137	482	440
Equity in net income of subsidiaries	0	0	0	0
Net income	662	535	1,717	1,570
Less: net income attributable to noncontrolling interests	(45)	(40)	(135)	(123)
Net income attributable to S&P Global Inc.	617	495	1,582	1,447
Comprehensive income	628	537	1,775	1,506
Eliminations
Condensed Income Statements, Captions [Line Items]
Revenue	(39)	(39)	(116)	(113)
Expenses:
Operating-related expenses	(39)	(39)	(116)	(113)
Selling and general expenses	0	0	0	0
Depreciation	0	0	0	0
Amortization of intangibles	0	0	0	0
Total expenses	(39)	(39)	(116)	(113)
Gain on dispositions	0	0	0	0
Operating profit	0	0	0	0
Other expense, net	0	0	0	0
Interest expense (income), net	0	0	0	0
Non-operating intercompany transactions	13	4	1,195	1,315
Income before taxes on income	(13)	(4)	(1,195)	(1,315)
Provision for taxes on income	0	0	0	0
Equity in net income of subsidiaries	(622)	(440)	(2,868)	(2,804)
Net income	(635)	(444)	(4,063)	(4,119)
Less: net income attributable to noncontrolling interests	(45)	(40)	(135)	(123)
Net income attributable to S&P Global Inc.	(680)	(484)	(4,198)	(4,242)
Comprehensive income	(633)	(441)	(4,062)	(4,118)
S&P Global Inc. | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Revenue	207	196	617	587
Expenses:
Operating-related expenses	40	30	126	105
Selling and general expenses	50	36	124	145
Depreciation	11	11	33	31
Amortization of intangibles	0	0	0	0
Total expenses	101	77	283	281
Gain on dispositions	(49)	0	(49)	0
Operating profit	155	119	383	306
Other expense, net	(5)	(5)	96	(21)
Interest expense (income), net	37	39	115	105
Non-operating intercompany transactions	100	90	291	277
Income before taxes on income	23	(5)	(119)	(55)
Provision for taxes on income	16	(65)	(28)	(52)
Equity in net income of subsidiaries	622	440	2,868	2,804
Net income	629	500	2,777	2,801
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to S&P Global Inc.	629	500	2,777	2,801
Comprehensive income	632	490	2,869	2,781
Standard & Poor's Financial Services LLC | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Revenue	491	422	1,416	1,318
Expenses:
Operating-related expenses	103	110	330	333
Selling and general expenses	58	79	222	222
Depreciation	3	2	9	6
Amortization of intangibles	0	0	0	0
Total expenses	164	191	561	561
Gain on dispositions	0	0	0	0
Operating profit	327	231	855	757
Other expense, net	0	0	0	0
Interest expense (income), net	0	1	0	2
Non-operating intercompany transactions	(6)	(11)	(42)	(54)
Income before taxes on income	333	241	897	809
Provision for taxes on income	80	94	239	240
Equity in net income of subsidiaries	0	0	0	0
Net income	253	147	658	569
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to S&P Global Inc.	253	147	658	569
Comprehensive income	253	147	658	569
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Revenue	1,030	967	3,047	2,929
Expenses:
Operating-related expenses	334	309	997	962
Selling and general expenses	252	264	769	830
Depreciation	6	7	19	23
Amortization of intangibles	29	33	92	91
Total expenses	621	613	1,877	1,906
Gain on dispositions	0	0	0	0
Operating profit	409	354	1,170	1,023
Other expense, net	13	(1)	8	(1)
Interest expense (income), net	(5)	(2)	(10)	(9)
Non-operating intercompany transactions	(107)	(83)	(1,444)	(1,538)
Income before taxes on income	508	440	2,616	2,571
Provision for taxes on income	93	108	271	252
Equity in net income of subsidiaries	0	0	0	0
Net income	415	332	2,345	2,319
Less: net income attributable to noncontrolling interests	0	0	0	0
Net income attributable to S&P Global Inc.	415	332	2,345	2,319
Comprehensive income	$ 376	$ 341	$ 2,310	$ 2,274