Revenues - Schedule of Changes in the Deferred Revenue Balances (Detail) - USD ($) $ in Millions	3 Months Ended		6 Months Ended
	Jun. 30, 2020	Jun. 30, 2019	Jun. 30, 2020	Jun. 30, 2019	Dec. 31, 2019
Change in Contract with Customer, Liability [Abstract]
Beginning Balance	$ 1,222	$ 1,183	$ 1,162	$ 1,076
Revenue recognized that was included in the deferred revenue balance at the beginning of the period	(456)	(454)	(844)	(694)
Increases due to amounts billable excluding amounts recognized as revenue during the period	334	347	790	689
Increases due to RDC acquisition during the period			20
Amount included in liabilities reclassified as held for sale		(3)		(3)
Effect of exchange rate changes	5	(2)	(23)	3
Total changes in deferred revenue	(117)	(112)	(57)	(5)
Ending Balance	1,105	1,071	1,105	1,071
Deferred revenue - current	1,001	953	1,001	953	$ 1,050
Deferred revenue - noncurrent	104	118	104	118	$ 112
MIS
Change in Contract with Customer, Liability [Abstract]
Beginning Balance	379	388	322	326
Revenue recognized that was included in the deferred revenue balance at the beginning of the period	(115)	(114)	(167)	(161)
Increases due to amounts billable excluding amounts recognized as revenue during the period	100	101	213	210
Increases due to RDC acquisition during the period			0
Amount included in liabilities reclassified as held for sale		0		0
Effect of exchange rate changes	1	1	(3)	1
Total changes in deferred revenue	(14)	(12)	43	50
Ending Balance	365	376	365	376
Deferred revenue - current	265	262	265	262
Deferred revenue - noncurrent	100	114	100	114
MA
Change in Contract with Customer, Liability [Abstract]
Beginning Balance	843	795	840	750
Revenue recognized that was included in the deferred revenue balance at the beginning of the period	(341)	(340)	(677)	(533)
Increases due to amounts billable excluding amounts recognized as revenue during the period	234	246	577	479
Increases due to RDC acquisition during the period			20
Amount included in liabilities reclassified as held for sale		(3)		(3)
Effect of exchange rate changes	4	(3)	(20)	2
Total changes in deferred revenue	(103)	(100)	(100)	(55)
Ending Balance	740	695	740	695
Deferred revenue - current	736	691	736	691
Deferred revenue - noncurrent	$ 4	$ 4	$ 4	$ 4