Revenues - Additional Information (Detail) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
MIS
Disaggregation of Revenue [Line Items]
Unbilled Receivables	$ 404	$ 346
MA
Disaggregation of Revenue [Line Items]
Unbilled Receivables	$ 89	$ 53

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

No definition available.

Name:	us-gaap_DisaggregationOfRevenueLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration