Goodwill and Other Intangible Assets - Changes In The Carrying Amount Of Goodwill (Details) - USD ($) $ in Millions	3 Months Ended	12 Months Ended
	Mar. 31, 2018	Dec. 31, 2017
Goodwill [Roll Forward]
Beginning balance	$ 6,022	$ 5,814
Acquisitions	0	17
Divestitures and other reductions	0	(9)
Foreign currency translation	46	200
Ending balance	6,068	6,022
Investment Servicing
Goodwill [Roll Forward]
Beginning balance	5,752	5,550
Acquisitions	0	17
Divestitures and other reductions	0	(9)
Foreign currency translation	45	194
Ending balance	5,797	5,752
Investment Management
Goodwill [Roll Forward]
Beginning balance	270	264
Acquisitions	0	0
Divestitures and other reductions	0	0
Foreign currency translation	1	6
Ending balance	$ 271	$ 270