Segment and Geographic Information - Disaggregation of Revenue (Details) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Reclassification from transaction revenue to non-transaction revenue										$ 27	$ 25
Total revenue	$ 1,735	$ 1,689	$ 1,704	$ 1,571	$ 1,536	$ 1,546	$ 1,609	$ 1,567	$ 6,699	6,258	6,063
Corporate
Disaggregation of Revenue [Line Items]
Total revenue									0	15	0
Intersegment Elimination
Disaggregation of Revenue [Line Items]
Total revenue									(128)	(125)	(110)
Ratings | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									3,106	2,883	2,988
Market Intelligence | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									1,959	1,833	1,683
Platts | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									844	815	774
Indices | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									918	837	728
Subscription
Disaggregation of Revenue [Line Items]
Total revenue									2,843	2,682	2,454
Subscription | Corporate
Disaggregation of Revenue [Line Items]
Total revenue									0	15	0
Subscription | Intersegment Elimination
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Subscription | Ratings | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Subscription | Market Intelligence | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									1,904	1,773	1,614
Subscription | Platts | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									774	750	704
Subscription | Indices | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									165	144	136
Non-subscription / Transaction
Disaggregation of Revenue [Line Items]
Total revenue									1,632	1,401	1,574
Non-subscription / Transaction | Corporate
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Non-subscription / Transaction | Intersegment Elimination
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Non-subscription / Transaction | Ratings | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									1,577	1,350	1,515
Non-subscription / Transaction | Market Intelligence | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									45	40	46
Non-subscription / Transaction | Platts | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									10	11	13
Non-subscription / Transaction | Indices | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Non-transaction
Disaggregation of Revenue [Line Items]
Total revenue									1,401	1,408	1,363
Non-transaction | Corporate
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Non-transaction | Intersegment Elimination
Disaggregation of Revenue [Line Items]
Total revenue									(128)	(125)	(110)
Non-transaction | Ratings | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									1,529	1,533	1,473
Non-transaction | Market Intelligence | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Non-transaction | Platts | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Non-transaction | Indices | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Asset-linked fees
Disaggregation of Revenue [Line Items]
Total revenue									623	542	484
Asset-linked fees | Corporate
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Asset-linked fees | Intersegment Elimination
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Asset-linked fees | Ratings | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Asset-linked fees | Market Intelligence | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									10	20	23
Asset-linked fees | Platts | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Asset-linked fees | Indices | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									613	522	461
Sales usage-based royalties
Disaggregation of Revenue [Line Items]
Total revenue									200	225	188
Sales usage-based royalties | Corporate
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Sales usage-based royalties | Intersegment Elimination
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Sales usage-based royalties | Ratings | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Sales usage-based royalties | Market Intelligence | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Sales usage-based royalties | Platts | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									60	54	57
Sales usage-based royalties | Indices | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									140	171	131
Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue									1,632	1,401	1,574
Services transferred at a point in time | Corporate
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Services transferred at a point in time | Intersegment Elimination
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Services transferred at a point in time | Ratings | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									1,577	1,350	1,515
Services transferred at a point in time | Market Intelligence | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									45	40	46
Services transferred at a point in time | Platts | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									10	11	13
Services transferred at a point in time | Indices | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									0	0	0
Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue									5,067	4,857	4,489
Services transferred over time | Corporate
Disaggregation of Revenue [Line Items]
Total revenue									0	15	0
Services transferred over time | Intersegment Elimination
Disaggregation of Revenue [Line Items]
Total revenue									(128)	(125)	(110)
Services transferred over time | Ratings | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									1,529	1,533	1,473
Services transferred over time | Market Intelligence | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									1,914	1,793	1,637
Services transferred over time | Platts | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									834	804	761
Services transferred over time | Indices | Operating Segments
Disaggregation of Revenue [Line Items]
Total revenue									$ 918	$ 837	$ 728