Goodwill, Customer Relationships and Other Intangible Assets - Additional Information (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2018	Mar. 31, 2017	Dec. 31, 2017
Finite-Lived Intangible Assets [Line Items]
Valuation allowance, available to reduce goodwill			$ 16
Acquired finite-lived intangible asset amortization expense	$ 194	$ 52
Intangible assets including goodwill, noncurrent	$ 20,291		$ 20,549
Acquired finite-lived intangible assets weighted average remaining useful lives	11 years 7 months 6 days
Customer Contracts And Relationships
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets weighted average remaining useful lives	11 years 10 months 24 days
Trade Names
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets weighted average remaining useful lives	4 years 7 months 6 days
Patents and Developed Technology
Finite-Lived Intangible Assets [Line Items]
Acquired finite-lived intangible assets weighted average remaining useful lives	4 years 7 months 6 days