Segment Information - Additional Information (Detail) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) segment lineOfBusiness	Dec. 31, 2017 USD ($)
Segment Reporting Information [Line Items]
Number of operating segments | segment	2
Number of reportable segments | segment	2
MIS
Segment Reporting Information [Line Items]
Number of Lines of Businesses | lineOfBusiness	5
MA
Segment Reporting Information [Line Items]
Number of Lines of Businesses | lineOfBusiness	3
2018 Restructuring Program | MIS
Segment Reporting Information [Line Items]
Cumulative expense incurred to date	$ 63.0
2018 Restructuring Program | MA
Segment Reporting Information [Line Items]
Cumulative expense incurred to date	$ 46.0
Accounting Standards Update 2017-07 | MIS
Segment Reporting Information [Line Items]
Reduction in direct operating costs selling general and administrative expense		$ 8.0
Accounting Standards Update 2017-07 | MA
Segment Reporting Information [Line Items]
Reduction in direct operating costs selling general and administrative expense		$ 4.0