Goodwill, Customer Relationships and Other Intangible Assets - Schedule of Goodwill, Customer Relationships, and Other Intangible Assets (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Goodwill [Line Items]
Goodwill	$ 21,476	$ 21,534
Indefinite-life intangible assets	278	269
Total other intangible assets, net	8,563	9,567
Customer relationships
Goodwill [Line Items]
Finite-lived intangible assets, net	6,633	7,596
Accumulated amortization	10,742	9,809
Capitalized software
Goodwill [Line Items]
Finite-lived intangible assets, net	1,567	1,599
Accumulated amortization	3,232	2,957
Trade names and patents
Goodwill [Line Items]
Finite-lived intangible assets, net	85	103
Accumulated amortization	$ 113	$ 91