Segment and Related Information - Operating Results by Segment (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2019	Mar. 31, 2018
Segment Reporting Information [Line Items]
Revenue	$ 1,571	$ 1,567
Operating Profit	705	711
Amortization of intangibles	32	24
Operating Segments
Segment Reporting Information [Line Items]
Operating Profit	751	757
Operating Segments | Ratings
Segment Reporting Information [Line Items]
Revenue	696	748
Operating Profit	363	408
Amortization of intangibles	1
Operating Segments | Market Intelligence
Segment Reporting Information [Line Items]
Revenue	482	439
Operating Profit	145	110
Amortization of intangibles	18	18
Operating Segments | Platts
Segment Reporting Information [Line Items]
Revenue	207	196
Operating Profit	94	90
Amortization of intangibles	3	5
Operating Segments | Indices
Segment Reporting Information [Line Items]
Revenue	217	212
Operating Profit	149	149
Amortization of intangibles	1	1
Corporate
Segment Reporting Information [Line Items]
Operating Profit	(46)	(46)
Amortization of intangibles	8
Retention related expenses	7
Intersegment Elimination
Segment Reporting Information [Line Items]
Revenue	$ (31)	$ (28)