Segment Information - Financial Information by Segment (Detail) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Segment Reporting Information, Operating Income (Loss) [Abstract]
Revenue	$ 6,218	$ 5,371	$ 4,829
Operating, SG&A	3,117	2,704	2,538
Adjusted Operating Income	3,101	2,667	2,291
Depreciation and amortization	257	220	200
Restructuring	0	50	60
Acquisition-Related Expenses	0	0	3
Loss pursuant to the divestiture of MAKS	0	9	14
Captive insurance company settlement			16
Operating income	2,844	2,388	1,998
Eliminations
Segment Reporting Information, Operating Income (Loss) [Abstract]
Revenue	(172)	(155)	(143)
Operating, SG&A	(172)	(155)	(143)
Adjusted Operating Income	0	0	0
Depreciation and amortization	0	0	0
Restructuring	0	0	0
Acquisition-Related Expenses			0
Loss pursuant to the divestiture of MAKS	0	0	0
Captive insurance company settlement			0
MIS
Segment Reporting Information, Operating Income (Loss) [Abstract]
Revenue	3,812	3,292	2,875
MIS | Operating Segments
Segment Reporting Information, Operating Income (Loss) [Abstract]
Revenue	3,977	3,440	3,009
Operating, SG&A	1,503	1,387	1,264
Adjusted Operating Income	2,474	2,053	1,745
Depreciation and amortization	72	70	71
Restructuring	(1)	19	31
Acquisition-Related Expenses			0
Loss pursuant to the divestiture of MAKS	0	0	0
Captive insurance company settlement			10
MA
Segment Reporting Information, Operating Income (Loss) [Abstract]
Revenue	2,406	2,079	1,954
MA | Operating Segments
Segment Reporting Information, Operating Income (Loss) [Abstract]
Revenue	2,413	2,086	1,963
Operating, SG&A	1,786	1,472	1,417
Adjusted Operating Income	627	614	546
Depreciation and amortization	185	150	129
Restructuring	1	31	29
Acquisition-Related Expenses			3
Loss pursuant to the divestiture of MAKS	$ 0	$ 9	14
Captive insurance company settlement			$ 6