Segment and Geographic Information - Segment Information (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Segment information
Revenue	$ 1,867	$ 1,846	$ 1,943	$ 1,786	$ 1,735	$ 1,689	$ 1,704	$ 1,571	$ 7,442	$ 6,699	$ 6,258
Operating Profit	$ 656	$ 944	$ 1,105	$ 912	$ 818	$ 891	$ 813	$ 705	3,617	3,226	2,790
Lease-related costs									144	157
Amortization of intangibles									123	122	122
Pre-tax gain (loss) on dispositions									16	49	0
Lease impairment charges									120	11	11
Ratings
Segment information
Technology-related impairment charge									11
Lease-related costs									5
Severance charges									4	11	8
Legal settlement expenses											74
Amortization of intangibles									7	2	2
Market Intelligence
Segment information
Lease-related costs									3
Severance charges									27	6
Amortization of intangibles									76	75	73
Pre-tax gain (loss) on dispositions									12
Pre-tax gain (loss) on dispositions										22
Acquisition-related costs										4
Business disposition and employee severance charges											7
Platts
Segment information
Lease-related costs									2
Severance charges									11	1
Amortization of intangibles									9	12	18
Pre-tax gain (loss) on dispositions										27
Indices
Segment information
Technology-related impairment charge									2
Lease-related costs									1
Severance charges									5
Amortization of intangibles									6	6	6
Lease impairment charges									4
Operating segments
Segment information
Operating Profit									3,936	3,438	3,021
Operating segments | Ratings
Segment information
Revenue									3,606	3,106	2,883
Operating Profit									2,223	1,783	1,554
Operating segments | Market Intelligence
Segment information
Revenue									2,106	1,959	1,833
Operating Profit									589	566	500
Operating segments | Platts
Segment information
Revenue									878	844	815
Operating Profit									458	457	401
Operating segments | Indices
Segment information
Revenue									989	918	837
Operating Profit									666	632	566
Corporate
Segment information
Revenue									0	0	15
Operating Profit									(319)	(212)	(231)
Severance charges									19	7	10
Amortization of intangibles									26	28	23
Acquisition-related costs									24
Lease impairment charges									116	11	11
Non-cash acquisition and disposition-related costs/adjustments									12	21	31
Gain related to an acquisition									1
Intersegment Elimination
Segment information
Revenue									$ (137)	$ (128)	$ (125)