Condensed Consolidating Financial Statements - Statement of Income (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Condensed Income Statements, Captions [Line Items]
Revenue	$ 1,735	$ 1,689	$ 1,704	$ 1,571	$ 1,536	$ 1,546	$ 1,609	$ 1,567	$ 6,699	$ 6,258	$ 6,063
Expenses:
Operating-related expenses									1,801	1,698	1,694
Selling and general expenses									1,517	1,564	1,606
Depreciation									82	84	82
Amortization of intangibles									122	122	98
Total expenses									3,522	3,468	3,480
Gain on dispositions									(49)	0	0
Operating profit	818	891	813	705	704	704	672	711	3,226	2,790	2,583
Other expense (income), net									98	(25)	(27)
Interest expense (income), net									198	134	149
Non-operating intercompany transactions									0	0	0
Income before taxes on income									2,930	2,681	2,461
(Benefit) Provision for taxes on income									627	560	823
Equity in net income of subsidiaries									0	0	0
Net income	585	662	602	453	551	535	501	534	2,303	2,121	1,638
Less: net income attributable to noncontrolling interests									(180)	(163)	(142)
Net income attributable to S&P Global Inc.	$ 541	$ 617	$ 555	$ 410	$ 512	$ 495	$ 461	$ 491	2,123	1,958	1,496
Comprehensive income									2,421	2,018	1,762
Eliminations
Condensed Income Statements, Captions [Line Items]
Revenue									(157)	(153)	(138)
Expenses:
Operating-related expenses									(157)	(153)	(138)
Selling and general expenses									0	0	0
Depreciation									0	0	0
Amortization of intangibles									0	0	0
Total expenses									(157)	(153)	(138)
Gain on dispositions									0
Operating profit									0	0	0
Other expense (income), net									0	0	0
Interest expense (income), net									0	0	0
Non-operating intercompany transactions									1,200	1,584	2,175
Income before taxes on income									(1,200)	(1,584)	(2,175)
(Benefit) Provision for taxes on income									0	0	0
Equity in net income of subsidiaries									(3,405)	(3,575)	(3,808)
Net income									(4,605)	(5,159)	(5,983)
Less: net income attributable to noncontrolling interests									(180)	(163)	(142)
Net income attributable to S&P Global Inc.									(4,785)	(5,322)	(6,125)
Comprehensive income									(4,602)	(5,159)	(5,982)
S&P Global Inc. | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Revenue									812	776	717
Expenses:
Operating-related expenses									158	124	89
Selling and general expenses									133	177	197
Depreciation									44	46	31
Amortization of intangibles									0	0	0
Total expenses									335	347	317
Gain on dispositions									(49)
Operating profit									526	429	400
Other expense (income), net									91	(27)	(16)
Interest expense (income), net									213	143	163
Non-operating intercompany transactions									378	363	365
Income before taxes on income									(156)	(50)	(112)
(Benefit) Provision for taxes on income									(74)	(14)	26
Equity in net income of subsidiaries									3,405	3,576	3,808
Net income									3,323	3,540	3,670
Less: net income attributable to noncontrolling interests									0	0	0
Net income attributable to S&P Global Inc.									3,323	3,540	3,670
Comprehensive income									3,446	3,510	3,694
Standard & Poor's Financial Services LLC | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Revenue									1,898	1,695	1,780
Expenses:
Operating-related expenses									440	434	482
Selling and general expenses									329	292	345
Depreciation									12	7	11
Amortization of intangibles									0	0	0
Total expenses									781	733	838
Gain on dispositions									0
Operating profit									1,117	962	942
Other expense (income), net									0	0	0
Interest expense (income), net									0	2	0
Non-operating intercompany transactions									(48)	(75)	(77)
Income before taxes on income									1,165	1,035	1,019
(Benefit) Provision for taxes on income									285	250	370
Equity in net income of subsidiaries									0	(1)	0
Net income									880	784	649
Less: net income attributable to noncontrolling interests									0	0	0
Net income attributable to S&P Global Inc.									880	784	649
Comprehensive income									880	783	649
Non-Guarantor Subsidiaries | Reportable Legal Entities
Condensed Income Statements, Captions [Line Items]
Revenue									4,146	3,940	3,704
Expenses:
Operating-related expenses									1,360	1,293	1,261
Selling and general expenses									1,055	1,095	1,064
Depreciation									26	31	40
Amortization of intangibles									122	122	98
Total expenses									2,563	2,541	2,463
Gain on dispositions									0
Operating profit									1,583	1,399	1,241
Other expense (income), net									7	2	(11)
Interest expense (income), net									(15)	(11)	(14)
Non-operating intercompany transactions									(1,530)	(1,872)	(2,463)
Income before taxes on income									3,121	3,280	3,729
(Benefit) Provision for taxes on income									416	324	427
Equity in net income of subsidiaries									0	0	0
Net income									2,705	2,956	3,302
Less: net income attributable to noncontrolling interests									0	0	0
Net income attributable to S&P Global Inc.									2,705	2,956	3,302
Comprehensive income									$ 2,697	$ 2,884	$ 3,401