Segment and Related Information - Operating Results by Segment (Details) - USD ($) $ in Millions	3 Months Ended	6 Months Ended
Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019
Segment Reporting Information [Line Items]
Revenue	$ 1,943	$ 1,704	$ 3,729	$ 3,275
Operating Profit	1,105	813	2,017	1,518
Amortization of intangibles from acquisitions	32	31	61	63
Gain on disposition	1	0	8	0
Operating Segments
Segment Reporting Information [Line Items]
Operating Profit	1,147	871	2,108	1,622
Operating Segments \| Ratings
Segment Reporting Information [Line Items]
Revenue	1,006	801	1,831	1,497
Operating Profit	693	460	1,213	828
Employee severance charges		11		11
Amortization of intangibles from acquisitions	2	1	2	1
Operating Segments \| Market Intelligence
Segment Reporting Information [Line Items]
Revenue	516	487	1,034	969
Operating Profit	159	137	306	271
Employee severance charges		1	2	1
Amortization of intangibles from acquisitions	20	19	39	37
Gain on disposition	1		8
Operating Segments \| Platts
Segment Reporting Information [Line Items]
Revenue	217	213	433	420
Operating Profit	124	111	236	211
Employee severance charges		1		1
Amortization of intangibles from acquisitions	2	3	4	7
Operating Segments \| Indices
Segment Reporting Information [Line Items]
Revenue	240	235	499	452
Operating Profit	171	163	353	312
Amortization of intangibles from acquisitions	1	1	3	3
Intersegment Elimination
Segment Reporting Information [Line Items]
Revenue	(36)	(32)	(68)	(63)
Corporate Unallocated
Segment Reporting Information [Line Items]
Operating Profit	(42)	(58)	(91)	(104)
Employee severance charges	3	7	10	7
Amortization of intangibles from acquisitions	7	7	13	14
Retention related expenses	$ 2	5	$ 7	11
Lease impairment		$ 5		$ 5

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