Revenues - Revenue Recognition Timing (Detail) - USD ($) $ in Millions	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Disaggregation of Revenue [Line Items]
Revenue recognized	$ 1,233	$ 1,240	$ 1,214	$ 1,142	$ 1,060	$ 1,081	$ 1,175	$ 1,127	$ 4,829	$ 4,443	$ 4,204
At Point in Time
Disaggregation of Revenue [Line Items]
Revenue recognized									1,941	1,785
Over Time
Disaggregation of Revenue [Line Items]
Revenue recognized									2,888	2,658
MIS
Disaggregation of Revenue [Line Items]
Revenue recognized									2,875	2,712	2,774
MIS | At Point in Time
Disaggregation of Revenue [Line Items]
Revenue recognized									1,809	1,686
MIS | Over Time
Disaggregation of Revenue [Line Items]
Revenue recognized									1,066	1,026
MA
Disaggregation of Revenue [Line Items]
Revenue recognized									1,954	1,731	$ 1,430
MA | At Point in Time
Disaggregation of Revenue [Line Items]
Revenue recognized									132	99
MA | Over Time
Disaggregation of Revenue [Line Items]
Revenue recognized									$ 1,822	$ 1,632