Segment and Related Information - Operating Results by Segment (Details) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2020	Sep. 30, 2019	Sep. 30, 2020	Sep. 30, 2019
Segment Reporting Information [Line Items]
Revenue	$ 1,846	$ 1,689	$ 5,575	$ 4,964
Operating Profit	944	891	2,960	2,408
Amortization of intangibles from acquisitions	32	29	94	92
Gain on disposition	8	49	16	49
Operating Segments
Segment Reporting Information [Line Items]
Operating Profit	980	936	3,088	2,558
Operating Segments | Ratings
Segment Reporting Information [Line Items]
Revenue	894	789	2,725	2,286
Operating Profit	544	477	1,758	1,305
Impairment charges	5		5
Employee severance charges		11		11
Amortization of intangibles from acquisitions	3		5	2
Operating Segments | Market Intelligence
Segment Reporting Information [Line Items]
Revenue	530	488	1,565	1,457
Operating Profit	164	161	469	431
Employee severance charges			2	1
Amortization of intangibles from acquisitions	19	19	58	56
Pre-tax gain (loss) on dispositions		22		22
Gain on disposition	4		12
Operating Segments | Platts
Segment Reporting Information [Line Items]
Revenue	222	212	654	632
Operating Profit	121	136	357	348
Employee severance charges				1
Amortization of intangibles from acquisitions	2	2	7	9
Pre-tax gain (loss) on dispositions		27		27
Operating Segments | Indices
Segment Reporting Information [Line Items]
Revenue	234	232	733	684
Operating Profit	151	162	504	474
Amortization of intangibles from acquisitions	1	1	4	4
Intersegment Elimination
Segment Reporting Information [Line Items]
Revenue	(34)	(32)	(102)	(95)
Corporate Unallocated
Segment Reporting Information [Line Items]
Operating Profit	(36)	(45)	(128)	(150)
Employee severance charges			10	7
Amortization of intangibles from acquisitions	7	7	20	21
Gain on disposition	4		4
Retention related expenses	$ 2	$ 6	$ 10	17
Lease impairment				$ 5