Segment and Related Information - Revenue Disaggregated by Type (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Disaggregation of Revenue [Line Items]
Total revenue	$ 2,016	$ 1,786
Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	595	444
Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	1,421	1,342
Subscription
Disaggregation of Revenue [Line Items]
Total revenue	781	748
Non-subscription / Transaction
Disaggregation of Revenue [Line Items]
Total revenue	595	444
Non-transaction
Disaggregation of Revenue [Line Items]
Total revenue	400	363
Asset-linked fees
Disaggregation of Revenue [Line Items]
Total revenue	183	160
Sales usage-based royalties
Disaggregation of Revenue [Line Items]
Total revenue	57	71
Operating Segments | Non-transaction
Disaggregation of Revenue [Line Items]
Total revenue		2
Operating Segments | Ratings
Disaggregation of Revenue [Line Items]
Total revenue	1,017	825
Operating Segments | Ratings | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	582	430
Operating Segments | Ratings | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	435	395
Operating Segments | Ratings | Subscription
Disaggregation of Revenue [Line Items]
Total revenue	0	0
Operating Segments | Ratings | Non-subscription / Transaction
Disaggregation of Revenue [Line Items]
Total revenue	582	430
Operating Segments | Ratings | Non-transaction
Disaggregation of Revenue [Line Items]
Total revenue	435	395
Operating Segments | Ratings | Asset-linked fees
Disaggregation of Revenue [Line Items]
Total revenue	0	0
Operating Segments | Ratings | Sales usage-based royalties
Disaggregation of Revenue [Line Items]
Total revenue	0	0
Operating Segments | Market Intelligence
Disaggregation of Revenue [Line Items]
Total revenue	539	519
Operating Segments | Market Intelligence | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	12	13
Operating Segments | Market Intelligence | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	527	506
Operating Segments | Market Intelligence | Subscription
Disaggregation of Revenue [Line Items]
Total revenue	527	505
Operating Segments | Market Intelligence | Non-subscription / Transaction
Disaggregation of Revenue [Line Items]
Total revenue	12	13
Operating Segments | Market Intelligence | Non-transaction
Disaggregation of Revenue [Line Items]
Total revenue	0	0
Operating Segments | Market Intelligence | Asset-linked fees
Disaggregation of Revenue [Line Items]
Total revenue	0	1
Operating Segments | Market Intelligence | Sales usage-based royalties
Disaggregation of Revenue [Line Items]
Total revenue	0	0
Operating Segments | Platts
Disaggregation of Revenue [Line Items]
Total revenue	225	215
Operating Segments | Platts | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	1	1
Operating Segments | Platts | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	224	214
Operating Segments | Platts | Subscription
Disaggregation of Revenue [Line Items]
Total revenue	208	197
Operating Segments | Platts | Non-subscription / Transaction
Disaggregation of Revenue [Line Items]
Total revenue	1	1
Operating Segments | Platts | Non-transaction
Disaggregation of Revenue [Line Items]
Total revenue	0	0
Operating Segments | Platts | Asset-linked fees
Disaggregation of Revenue [Line Items]
Total revenue	0	0
Operating Segments | Platts | Sales usage-based royalties
Disaggregation of Revenue [Line Items]
Total revenue	16	17
Operating Segments | Indices
Disaggregation of Revenue [Line Items]
Total revenue	270	259
Operating Segments | Indices | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	0	0
Operating Segments | Indices | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	270	259
Operating Segments | Indices | Subscription
Disaggregation of Revenue [Line Items]
Total revenue	46	46
Operating Segments | Indices | Non-subscription / Transaction
Disaggregation of Revenue [Line Items]
Total revenue	0	0
Operating Segments | Indices | Non-transaction
Disaggregation of Revenue [Line Items]
Total revenue	0	0
Operating Segments | Indices | Asset-linked fees
Disaggregation of Revenue [Line Items]
Total revenue	183	159
Operating Segments | Indices | Sales usage-based royalties
Disaggregation of Revenue [Line Items]
Total revenue	41	54
Intersegment Elimination
Disaggregation of Revenue [Line Items]
Total revenue	(35)	(32)
Intersegment Elimination | Services transferred at a point in time
Disaggregation of Revenue [Line Items]
Total revenue	0	0
Intersegment Elimination | Services transferred over time
Disaggregation of Revenue [Line Items]
Total revenue	(35)	(32)
Intersegment Elimination | Subscription
Disaggregation of Revenue [Line Items]
Total revenue	0	0
Intersegment Elimination | Non-subscription / Transaction
Disaggregation of Revenue [Line Items]
Total revenue	0	0
Intersegment Elimination | Non-transaction
Disaggregation of Revenue [Line Items]
Total revenue	(35)	(32)
Intersegment Elimination | Asset-linked fees
Disaggregation of Revenue [Line Items]
Total revenue	0	0
Intersegment Elimination | Sales usage-based royalties
Disaggregation of Revenue [Line Items]
Total revenue	$ 0	$ 0