Revenues - Schedule of Changes in the Deferred Revenue Balances (Detail) - USD ($) $ in Millions	3 Months Ended		9 Months Ended
	Sep. 30, 2021	Sep. 30, 2020	Sep. 30, 2021	Sep. 30, 2020	Dec. 31, 2020
Change in Contract with Customer, Liability [Abstract]
Beginning Balance	$ 1,235	$ 1,105	$ 1,187	$ 1,162
Revenue recognized that was included in the deferred revenue balance at the beginning of the period	(602)	(465)	(1,014)	(988)
Increases due to amounts billable excluding amounts recognized as revenue during the period	478	356	937	826
Increases due to acquisitions during the period	89	0	93	20
Effect of exchange rate changes	(14)	24	(17)	0
Total changes in deferred revenue	(49)	(85)	(1)	(142)
Ending Balance	1,186	1,020	1,186	1,020
Deferred revenue - current	1,099	918	1,099	918	$ 1,089
Deferred revenue - non-current	87	102	87	102	$ 98
MIS
Change in Contract with Customer, Liability [Abstract]
Beginning Balance	368	365	313	322
Revenue recognized that was included in the deferred revenue balance at the beginning of the period	(118)	(118)	(200)	(207)
Increases due to amounts billable excluding amounts recognized as revenue during the period	85	83	224	219
Increases due to acquisitions during the period	0	0	0	0
Effect of exchange rate changes	(2)	5	(4)	1
Total changes in deferred revenue	(35)	(30)	20	13
Ending Balance	333	335	333	335
Deferred revenue - current	247	237	247	237
Deferred revenue - non-current	86	98	86	98
MA
Change in Contract with Customer, Liability [Abstract]
Beginning Balance	867	740	874	840
Revenue recognized that was included in the deferred revenue balance at the beginning of the period	(484)	(347)	(814)	(781)
Increases due to amounts billable excluding amounts recognized as revenue during the period	393	273	713	607
Increases due to acquisitions during the period	89	0	93	20
Effect of exchange rate changes	(12)	19	(13)	(1)
Total changes in deferred revenue	(14)	(55)	(21)	(155)
Ending Balance	853	685	853	685
Deferred revenue - current	852	681	852	681
Deferred revenue - non-current	$ 1	$ 4	$ 1	$ 4