Schedule of Qualifying and Valuation Accounts (Details) - Allowance for Doubtful Accounts, Current [Member] - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Year	$ 3,504	$ 2,438	$ 2,191
Acquisitions and Dispositions	(17)	960
Charged to Costs and Expenses	3,168	3,022	2,034
Write-offs	(2,545)	(2,916)	(1,787)
Balance at End of Year	$ 4,110	$ 3,504	$ 2,438