Goodwill, Customer Relationships and Other Intangible Assets - Schedule of Goodwill by Segment (Details) - USD ($) $ in Millions	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Business Acquisition [Line Items]
Goodwill	$ 28,031	$ 30,475	$ 19,650
Business
Business Acquisition [Line Items]
Goodwill	20,447	20,197	9,372
Business | Medium and Small Business
Business Acquisition [Line Items]
Goodwill	5,193
Business | Enterprise
Business Acquisition [Line Items]
Goodwill	5,222
Business | International and Global Accounts
Business Acquisition [Line Items]
Goodwill	3,596
Business | Wholesale and Indirect
Business Acquisition [Line Items]
Goodwill	6,436
Consumer
Business Acquisition [Line Items]
Goodwill	$ 7,584	$ 10,278	$ 10,278