Goodwill and Other Intangible Assets - Changes In The Carrying Amount Of Goodwill (Details) - USD ($) $ in Millions	3 Months Ended	9 Months Ended	12 Months Ended
	Mar. 31, 2019	Sep. 30, 2020	Dec. 31, 2019
Goodwill [Roll Forward]
Beginning balance	$ 7,446	$ 7,556	$ 7,446
Acquisitions			122
Foreign currency translation		51	(12)
Ending balance		7,607	7,556
Finite-lived intangible assets acquired			93
Investment Servicing
Goodwill [Roll Forward]
Beginning balance	7,180	7,289	7,180
Acquisitions			122
Foreign currency translation		51	(13)
Ending balance		7,340	7,289
Finite-lived intangible assets acquired	93		93
Goodwill, period increase (decrease)	113
Investment Management
Goodwill [Roll Forward]
Beginning balance	$ 266	267	266
Acquisitions			0
Foreign currency translation		0	1
Ending balance		$ 267	267
Finite-lived intangible assets acquired			$ 0