Goodwill, Customer Relationships and Other Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019	Jan. 31, 2019	Jan. 01, 2019
Goodwill and Intangible Assets Disclosure [Abstract]
Amortization of intangible assets	$ 431	$ 429
Intangible assets, gross (including goodwill)	43,900
Control premium, percent			4.10%	4.50%
Goodwill impairment	$ 0	$ 6,506

Amount of loss from the write-down of an asset representing the future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

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