Condensed Consolidating Financial Statements - Statement of Cash Flows (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017
Operating Activities:
Net income	$ 534	$ 430
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	21	19
Amortization of intangibles	24	24
Provision for losses on accounts receivable	8	5
Stock-based compensation	13	19
Other	16	13
Changes in operating assets and liabilities, net of effect of acquisitions and dispositions:
Accounts receivable	7	12
Prepaid and other current assets	(21)	9
Accounts payable and accrued expenses	(289)	(235)
Unearned revenue	27	(6)
Accrued legal settlements	(29)	(1)
Other current liabilities	19	(58)
Net change in prepaid/accrued income taxes	74	146
Net change in other assets and liabilities	(44)	(24)
Cash provided by operating activities	360	353
Investing Activities:
Capital expenditures	(33)	(23)
Acquisitions, net of cash acquired	(57)	(1)
Changes in short-term investments	3	0
Proceeds from dispositions	0	2
Cash used for investing activities	(87)	(22)
Financing Activities:
Dividends paid to shareholders	(127)	(106)
Distributions to noncontrolling interest holders	(50)	(24)
Repurchase of treasury shares	(1,100)	(201)
Exercise of stock options	10	29
Employee withholding tax on share-based payments	(49)	(44)
Intercompany financing activities	0	0
Cash used for financing activities	(1,316)	(346)
Effect of exchange rate changes on cash from continuing operations	20	34
Net change in cash and cash equivalents	(1,023)	19
Cash and cash equivalents at beginning of period	2,779	2,392
Cash and cash equivalents at end of period	1,756	2,411
Eliminations
Operating Activities:
Net income	(2,528)	(2,062)
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	0	0
Amortization of intangibles	0	0
Provision for losses on accounts receivable	0	0
Stock-based compensation	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
Accrued legal settlements	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	(2,528)	(2,062)
Investing Activities:
Capital expenditures	0	0
Acquisitions, net of cash acquired	0	0
Changes in short-term investments	0
Proceeds from dispositions		0
Cash used for investing activities	0	0
Financing Activities:
Dividends paid to shareholders	0	0
Distributions to noncontrolling interest holders	0	0
Repurchase of treasury shares	0	0
Exercise of stock options	0	0
Employee withholding tax on share-based payments	0	0
Intercompany financing activities	2,528	2,062
Cash used for financing activities	2,528	2,062
Effect of exchange rate changes on cash from continuing operations	0	0
Net change in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
S&P Global Inc.
Investing Activities:
Changes in short-term investments	0
S&P Global Inc. | Reportable Legal Entities
Operating Activities:
Net income	1,507	1,236
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	8	7
Amortization of intangibles	0	0
Provision for losses on accounts receivable	0	1
Stock-based compensation	5	7
Other	(71)	5
Changes in operating assets and liabilities, net of effect of acquisitions and dispositions:
Accounts receivable	5	8
Prepaid and other current assets	(18)	8
Accounts payable and accrued expenses	(60)	(61)
Unearned revenue	(4)	5
Accrued legal settlements	(29)	0
Other current liabilities	22	(35)
Net change in prepaid/accrued income taxes	73	123
Net change in other assets and liabilities	(37)	(6)
Cash provided by operating activities	1,401	1,298
Investing Activities:
Capital expenditures	(23)	(4)
Acquisitions, net of cash acquired	0	0
Proceeds from dispositions		0
Cash used for investing activities	(23)	(4)
Financing Activities:
Dividends paid to shareholders	(127)	(106)
Distributions to noncontrolling interest holders	0	0
Repurchase of treasury shares	(1,100)	(201)
Exercise of stock options	10	29
Employee withholding tax on share-based payments	(49)	(44)
Intercompany financing activities	(158)	(1,056)
Cash used for financing activities	(1,424)	(1,378)
Effect of exchange rate changes on cash from continuing operations	(5)	0
Net change in cash and cash equivalents	(51)	(84)
Cash and cash equivalents at beginning of period	632	711
Cash and cash equivalents at end of period	581	627
Standard & Poor's Financial Services LLC
Investing Activities:
Changes in short-term investments	0
Standard & Poor's Financial Services LLC | Reportable Legal Entities
Operating Activities:
Net income	177	148
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	2	3
Amortization of intangibles	0	0
Provision for losses on accounts receivable	2	1
Stock-based compensation	3	4
Other	0	0
Changes in operating assets and liabilities, net of effect of acquisitions and dispositions:
Accounts receivable	(27)	(59)
Prepaid and other current assets	1	3
Accounts payable and accrued expenses	(79)	12
Unearned revenue	28	25
Accrued legal settlements	0	(1)
Other current liabilities	(2)	(3)
Net change in prepaid/accrued income taxes	1	0
Net change in other assets and liabilities	0	(4)
Cash provided by operating activities	106	129
Investing Activities:
Capital expenditures	(6)	(4)
Acquisitions, net of cash acquired	0	0
Proceeds from dispositions		0
Cash used for investing activities	(6)	(4)
Financing Activities:
Dividends paid to shareholders	0	0
Distributions to noncontrolling interest holders	0	0
Repurchase of treasury shares	0	0
Exercise of stock options	0	0
Employee withholding tax on share-based payments	0	0
Intercompany financing activities	(100)	(125)
Cash used for financing activities	(100)	(125)
Effect of exchange rate changes on cash from continuing operations	0	0
Net change in cash and cash equivalents	0	0
Cash and cash equivalents at beginning of period	0	0
Cash and cash equivalents at end of period	0	0
Non-Guarantor Subsidiaries
Investing Activities:
Changes in short-term investments	3
Non-Guarantor Subsidiaries | Reportable Legal Entities
Operating Activities:
Net income	1,378	1,108
Adjustments to reconcile net income to cash provided by operating activities:
Depreciation	11	9
Amortization of intangibles	24	24
Provision for losses on accounts receivable	6	3
Stock-based compensation	5	8
Other	87	8
Changes in operating assets and liabilities, net of effect of acquisitions and dispositions:
Accounts receivable	29	63
Prepaid and other current assets	(4)	(2)
Accounts payable and accrued expenses	(150)	(186)
Unearned revenue	3	(36)
Accrued legal settlements	0	0
Other current liabilities	(1)	(20)
Net change in prepaid/accrued income taxes	0	23
Net change in other assets and liabilities	(7)	(14)
Cash provided by operating activities	1,381	988
Investing Activities:
Capital expenditures	(4)	(15)
Acquisitions, net of cash acquired	(57)	(1)
Proceeds from dispositions		2
Cash used for investing activities	(58)	(14)
Financing Activities:
Dividends paid to shareholders	0	0
Distributions to noncontrolling interest holders	(50)	(24)
Repurchase of treasury shares	0	0
Exercise of stock options		0
Employee withholding tax on share-based payments	0	0
Intercompany financing activities	(2,270)	(881)
Cash used for financing activities	(2,320)	(905)
Effect of exchange rate changes on cash from continuing operations	25	34
Net change in cash and cash equivalents	(972)	103
Cash and cash equivalents at beginning of period	2,147	1,681
Cash and cash equivalents at end of period	$ 1,175	$ 1,784