Condensed Consolidating Financial Statements - Statement of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended			9 Months Ended
	Sep. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Operating Activities:
Net income	$ 498		$ 662	$ 2,029	$ 1,717
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	20		20	60	61
Amortization of intangibles	32		29	94	92
Provision for losses on accounts receivable				16	17
Deferred income taxes				(14)	33
Stock-based compensation				60	53
Gain on dispositions	(8)		(49)	(16)	(49)
Pension settlement charges, net of taxes				2	85
Loss on extinguishment of debt	279		0	279	0
Other				50	49
Changes in operating assets and liabilities, net of effect of acquisitions and dispositions:
Accounts receivable				172	(50)
Prepaid and other current assets				(52)	(59)
Accounts payable and accrued expenses				(97)	(54)
Unearned revenue				(158)	(27)
Other current liabilities				(28)	(82)
Net change in prepaid/accrued income taxes				28	40
Net change in other assets and liabilities				1	(54)
Cash provided by operating activities				2,426	1,772
Investing Activities:
Capital expenditures				(43)	(77)
Acquisitions, net of cash acquired				(189)	(25)
Proceeds from dispositions				9	85
Changes in short-term investments				19	(3)
Cash used for investing activities				(204)	(20)
Financing Activities:
Proceeds from issuance of senior notes, net				1,276	0
Payments on senior notes				(1,394)	0
Dividends paid to shareholders				(484)	(421)
Distributions to noncontrolling interest holders, net				(143)	(100)
Repurchase of treasury shares		$ (1,164)		(1,164)	(1,144)
Exercise of stock options				14	38
Employee withholding tax on share-based payments and other				(55)	(57)
Intercompany financing activities				0	0
Cash used for financing activities				(1,950)	(1,684)
Effect of exchange rate changes on cash				10	(7)
Net change in cash, cash equivalents, and restricted cash				282	61
Cash, cash equivalents, and restricted cash at beginning of period		2,886		2,886	1,958
Cash, cash equivalents, and restricted cash at end of period	3,168		2,019	3,168	2,019
Eliminations
Operating Activities:
Net income	(786)		(635)	(4,520)	(4,063)
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	0		0	0	0
Amortization of intangibles	0		0	0	0
Provision for losses on accounts receivable				0	0
Deferred income taxes				0	0
Stock-based compensation				0	0
Gain on dispositions	0			0	0
Pension settlement charges, net of taxes				0	0
Loss on extinguishment of debt	0			0
Other				0	0
Changes in operating assets and liabilities, net of effect of acquisitions and dispositions:
Accounts receivable				0	0
Prepaid and other current assets				0	0
Accounts payable and accrued expenses				0	0
Unearned revenue				0	0
Other current liabilities				0	0
Net change in prepaid/accrued income taxes				0	0
Net change in other assets and liabilities				0	0
Cash provided by operating activities				(4,520)	(4,063)
Investing Activities:
Capital expenditures				0	0
Acquisitions, net of cash acquired				0	0
Proceeds from dispositions				0	0
Changes in short-term investments				0	0
Cash used for investing activities				0	0
Financing Activities:
Proceeds from issuance of senior notes, net				0
Payments on senior notes				0
Dividends paid to shareholders				0	0
Distributions to noncontrolling interest holders, net				0	0
Repurchase of treasury shares				0	0
Exercise of stock options				0	0
Employee withholding tax on share-based payments and other				0	0
Intercompany financing activities				4,520	4,063
Cash used for financing activities				4,520	4,063
Effect of exchange rate changes on cash				0	0
Net change in cash, cash equivalents, and restricted cash				0	0
Cash, cash equivalents, and restricted cash at beginning of period		0		0	0
Cash, cash equivalents, and restricted cash at end of period	0		0	0	0
S&P Global Inc. | Reportable Legal Entities
Operating Activities:
Net income	530		629	3,116	2,777
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	9		11	30	33
Amortization of intangibles	0		0	0	0
Provision for losses on accounts receivable				4	5
Deferred income taxes				(12)	22
Stock-based compensation				24	17
Gain on dispositions	(5)			(5)	(49)
Pension settlement charges, net of taxes				0	85
Loss on extinguishment of debt	279			279
Other				22	12
Changes in operating assets and liabilities, net of effect of acquisitions and dispositions:
Accounts receivable				9	(90)
Prepaid and other current assets				(46)	(20)
Accounts payable and accrued expenses				(19)	(17)
Unearned revenue				12	35
Other current liabilities				(18)	(62)
Net change in prepaid/accrued income taxes				57	31
Net change in other assets and liabilities				20	(56)
Cash provided by operating activities				3,473	2,723
Investing Activities:
Capital expenditures				(10)	(32)
Acquisitions, net of cash acquired				0	0
Proceeds from dispositions				0	85
Changes in short-term investments				0	0
Cash used for investing activities				(10)	53
Financing Activities:
Proceeds from issuance of senior notes, net				1,276
Payments on senior notes				(1,394)
Dividends paid to shareholders				(484)	(421)
Distributions to noncontrolling interest holders, net				0	0
Repurchase of treasury shares				(1,164)	(1,144)
Exercise of stock options				11	36
Employee withholding tax on share-based payments and other				(55)	(55)
Intercompany financing activities				(965)	(1,377)
Cash used for financing activities				(2,775)	(2,961)
Effect of exchange rate changes on cash				0	0
Net change in cash, cash equivalents, and restricted cash				688	(185)
Cash, cash equivalents, and restricted cash at beginning of period		1,130		1,130	694
Cash, cash equivalents, and restricted cash at end of period	1,818		509	1,818	509
Standard & Poor's Financial Services LLC | Reportable Legal Entities
Operating Activities:
Net income	257		253	916	658
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	2		3	8	9
Amortization of intangibles	0		0	0	0
Provision for losses on accounts receivable				4	1
Deferred income taxes				0	1
Stock-based compensation				10	9
Gain on dispositions	0			0	0
Pension settlement charges, net of taxes				0	0
Loss on extinguishment of debt	0			0
Other				0	6
Changes in operating assets and liabilities, net of effect of acquisitions and dispositions:
Accounts receivable				(46)	(86)
Prepaid and other current assets				21	2
Accounts payable and accrued expenses				(16)	(1)
Unearned revenue				4	21
Other current liabilities				(5)	(6)
Net change in prepaid/accrued income taxes				(28)	1
Net change in other assets and liabilities				(13)	(3)
Cash provided by operating activities				855	612
Investing Activities:
Capital expenditures				(5)	(3)
Acquisitions, net of cash acquired				0	0
Proceeds from dispositions				0	0
Changes in short-term investments				0	0
Cash used for investing activities				(5)	(3)
Financing Activities:
Proceeds from issuance of senior notes, net				0
Payments on senior notes				0
Dividends paid to shareholders				0	0
Distributions to noncontrolling interest holders, net				0	0
Repurchase of treasury shares				0	0
Exercise of stock options				0	0
Employee withholding tax on share-based payments and other				0	0
Intercompany financing activities				(850)	(609)
Cash used for financing activities				(850)	(609)
Effect of exchange rate changes on cash				0	0
Net change in cash, cash equivalents, and restricted cash				0	0
Cash, cash equivalents, and restricted cash at beginning of period		0		0	0
Cash, cash equivalents, and restricted cash at end of period	0		0	0	0
Non-Guarantor Subsidiaries | Reportable Legal Entities
Operating Activities:
Net income	497		415	2,517	2,345
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	9		6	22	19
Amortization of intangibles	32		29	94	92
Provision for losses on accounts receivable				8	11
Deferred income taxes				(2)	10
Stock-based compensation				26	27
Gain on dispositions	(3)			(11)	0
Pension settlement charges, net of taxes				2	0
Loss on extinguishment of debt	0			0
Other				28	31
Changes in operating assets and liabilities, net of effect of acquisitions and dispositions:
Accounts receivable				209	126
Prepaid and other current assets				(27)	(41)
Accounts payable and accrued expenses				(62)	(36)
Unearned revenue				(174)	(83)
Other current liabilities				(5)	(14)
Net change in prepaid/accrued income taxes				(1)	8
Net change in other assets and liabilities				(6)	5
Cash provided by operating activities				2,618	2,500
Investing Activities:
Capital expenditures				(28)	(42)
Acquisitions, net of cash acquired				(189)	(25)
Proceeds from dispositions				9	0
Changes in short-term investments				19	(3)
Cash used for investing activities				(189)	(70)
Financing Activities:
Proceeds from issuance of senior notes, net				0
Payments on senior notes				0
Dividends paid to shareholders				0	0
Distributions to noncontrolling interest holders, net				(143)	(100)
Repurchase of treasury shares				0	0
Exercise of stock options				3	2
Employee withholding tax on share-based payments and other				0	(2)
Intercompany financing activities				(2,705)	(2,077)
Cash used for financing activities				(2,845)	(2,177)
Effect of exchange rate changes on cash				10	(7)
Net change in cash, cash equivalents, and restricted cash				(406)	246
Cash, cash equivalents, and restricted cash at beginning of period		$ 1,756		1,756	1,264
Cash, cash equivalents, and restricted cash at end of period	$ 1,350		$ 1,510	$ 1,350	$ 1,510