Revenues - Consolidated Revenue Information by Geographic Area (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2021	Mar. 31, 2020
Segment Reporting Information [Line Items]
Revenue	$ 1,600	$ 1,290
MIS
Segment Reporting Information [Line Items]
Revenue	1,036	794
MA
Segment Reporting Information [Line Items]
Revenue	564	496
United States
Segment Reporting Information [Line Items]
Revenue	885	714
United States | MIS
Segment Reporting Information [Line Items]
Revenue	647	503
United States | MA
Segment Reporting Information [Line Items]
Revenue	238	211
EMEA
Segment Reporting Information [Line Items]
Revenue	478	363
EMEA | MIS
Segment Reporting Information [Line Items]
Revenue	248	171
EMEA | MA
Segment Reporting Information [Line Items]
Revenue	230	192
Asia-Pacific
Segment Reporting Information [Line Items]
Revenue	156	136
Asia-Pacific | MIS
Segment Reporting Information [Line Items]
Revenue	97	81
Asia-Pacific | MA
Segment Reporting Information [Line Items]
Revenue	59	55
Americas
Segment Reporting Information [Line Items]
Revenue	81	77
Americas | MIS
Segment Reporting Information [Line Items]
Revenue	44	39
Americas | MA
Segment Reporting Information [Line Items]
Revenue	37	38
Non-U.S.
Segment Reporting Information [Line Items]
Revenue	715	576
Non-U.S. | MIS
Segment Reporting Information [Line Items]
Revenue	389	291
Non-U.S. | MA
Segment Reporting Information [Line Items]
Revenue	$ 326	$ 285