Revenues - Consolidated Revenue Information by Geographic Area (Detail) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Segment Reporting Information [Line Items]
Revenue	$ 1,290	$ 1,142
MIS
Segment Reporting Information [Line Items]
Revenue	794	670
MA
Segment Reporting Information [Line Items]
Revenue	496	472
United States
Segment Reporting Information [Line Items]
Revenue	714	612
United States | MIS
Segment Reporting Information [Line Items]
Revenue	503	411
United States | MA
Segment Reporting Information [Line Items]
Revenue	211	201
EMEA
Segment Reporting Information [Line Items]
Revenue	363	333
EMEA | MIS
Segment Reporting Information [Line Items]
Revenue	171	149
EMEA | MA
Segment Reporting Information [Line Items]
Revenue	192	184
Asia-Pacific
Segment Reporting Information [Line Items]
Revenue	136	132
Asia-Pacific | MIS
Segment Reporting Information [Line Items]
Revenue	81	79
Asia-Pacific | MA
Segment Reporting Information [Line Items]
Revenue	55	53
Americas
Segment Reporting Information [Line Items]
Revenue	77	65
Americas | MIS
Segment Reporting Information [Line Items]
Revenue	39	31
Americas | MA
Segment Reporting Information [Line Items]
Revenue	38	34
Non-U.S.
Segment Reporting Information [Line Items]
Revenue	576	530
Non-U.S. | MIS
Segment Reporting Information [Line Items]
Revenue	291	259
Non-U.S. | MA
Segment Reporting Information [Line Items]
Revenue	$ 285	$ 271