Segment and Related Information - Operating Results by Segment (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Revenue	$ 2,016	$ 1,786
Operating Profit	1,081	912
Amortization of intangibles from acquisitions	31	29
Gain on disposition	2	7
Non-transaction
Segment Reporting Information [Line Items]
Revenue	400	363
Operating Segments
Segment Reporting Information [Line Items]
Operating Profit	1,167	961
Operating Segments \| Non-transaction
Segment Reporting Information [Line Items]
Revenue		2
Operating Segments \| Ratings
Segment Reporting Information [Line Items]
Revenue	1,017	825
Operating Profit	681	520
Amortization of intangibles from acquisitions	5
Operating Segments \| Ratings \| Non-transaction
Segment Reporting Information [Line Items]
Revenue	435	395
Operating Segments \| Market Intelligence
Segment Reporting Information [Line Items]
Revenue	539	519
Operating Profit	166	147
Amortization of intangibles from acquisitions	16	19
Gain on disposition	2	7
Employee severance charges		2
Operating Segments \| Market Intelligence \| Non-transaction
Segment Reporting Information [Line Items]
Revenue	0	0
Operating Segments \| Platts
Segment Reporting Information [Line Items]
Revenue	225	215
Operating Profit	129	112
Amortization of intangibles from acquisitions	2	2
Operating Segments \| Platts \| Non-transaction
Segment Reporting Information [Line Items]
Revenue	0	0
Operating Segments \| Indices
Segment Reporting Information [Line Items]
Revenue	270	259
Operating Profit	191	182
Amortization of intangibles from acquisitions	1	1
Operating Segments \| Indices \| Non-transaction
Segment Reporting Information [Line Items]
Revenue	0	0
Intersegment Elimination
Segment Reporting Information [Line Items]
Revenue	(35)	(32)
Intersegment Elimination \| Non-transaction
Segment Reporting Information [Line Items]
Revenue	(35)	(32)
Corporate Unallocated
Segment Reporting Information [Line Items]
Operating Profit	(86)	(49)
Amortization of intangibles from acquisitions	7	7
Employee severance charges		7
Acquisition-related costs	49
Retention related expenses	$ 2	$ 5

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