Goodwill, Customer Relationships and Other Intangible Assets - Schedule of Goodwill (Details) - USD ($) $ in Millions	Sep. 30, 2020	Dec. 31, 2019
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 9,360	$ 9,360
Finite-lived intangible assets, net	454	779
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	179	468
Accumulated amortization	5,520	5,231
Other Intangible Assets
Finite-Lived Intangible Assets [Line Items]
Finite-lived intangible assets, net	275	311
Accumulated amortization	$ 1,813	$ 1,780