Goodwill, Customer Relationships and Other Intangible Assets - Schedule of Goodwill and Other Intangible Assets (Details) - USD ($) $ in Millions	Sep. 30, 2021	Dec. 31, 2020
Finite-Lived Intangible Assets [Line Items]
Goodwill	$ 6,667	$ 7,405
Other intangible assets, net	5,907	6,605
Customer relationships
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	5,487	6,156
Accumulated amortization	2,617	2,246
Capitalized software
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	387	401
Accumulated amortization	322	256
Trade names
Finite-Lived Intangible Assets [Line Items]
Other intangible assets, net	33	48
Accumulated amortization	$ 98	$ 83