Goodwill And Other Acquired Intangible Assets - Activity in Goodwill (Detail) - USD ($) $ in Millions	9 Months Ended	12 Months Ended
Sep. 30, 2021	Dec. 31, 2020
Goodwill [Roll Forward]
Beginning balance, goodwill gross	$ 4,568	$ 3,734
Beginning balance, Accumulated impairment charge	(12)	(12)
Beginning balance, goodwill net	4,556	3,722
Additions/ adjustments	1,478	626
Foreign currency translation adjustments	(136)	208
Ending balance, goodwill gross	5,910	4,568
Ending balance, Accumulated impairment charge	(12)	(12)
Ending balance, goodwill net	5,898	4,556
MIS
Goodwill [Roll Forward]
Beginning balance, goodwill gross	311	315
Beginning balance, Accumulated impairment charge	0	0
Beginning balance, goodwill net	311	315
Additions/ adjustments	90	(2)
Foreign currency translation adjustments	(5)	(2)
Ending balance, goodwill gross	396	311
Ending balance, Accumulated impairment charge	0	0
Ending balance, goodwill net	396	311
MA
Goodwill [Roll Forward]
Beginning balance, goodwill gross	4,257	3,419
Beginning balance, Accumulated impairment charge	(12)	(12)
Beginning balance, goodwill net	4,245	3,407
Additions/ adjustments	1,388	628
Foreign currency translation adjustments	(131)	210
Ending balance, goodwill gross	5,514	4,257
Ending balance, Accumulated impairment charge	(12)	(12)
Ending balance, goodwill net	$ 5,502	$ 4,245

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase in asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized resulting from a business combination.

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Amount before accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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Amount of increase (decrease) from foreign currency translation adjustments and purchase accounting adjustments of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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