Goodwill, Customer Relationships and Other Intangible Assets - Schedule of Goodwill, Customer Relationships, and Other Intangible Assets (Details) - USD ($) $ in Millions	Mar. 31, 2020	Dec. 31, 2019
Goodwill [Line Items]
Goodwill	$ 21,473	$ 21,534
Finite-lived intangible assets, net	7,245	7,596
Indefinite-life intangible assets	269	269
Total other intangible assets, net	1,981	1,971
Customer relationships
Goodwill [Line Items]
Finite-lived intangible assets, net	7,245	7,596
Accumulated amortization	10,114	9,809
Computer Software, Intangible Asset
Goodwill [Line Items]
Finite-lived intangible assets, net	1,617	1,599
Accumulated amortization	3,031	2,957
Trade Names and Patents
Goodwill [Line Items]
Finite-lived intangible assets, net	95	103
Accumulated amortization	$ 98	$ 91