Schedule II (Details) (Allowance for doubtful accounts, Current [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Allowance for doubtful accounts, Current [Member]
Movement in Valuation Allowances and Reserves [Roll Forward]
Balance at Beginning of Period	$ 162	$ 202	$ 202
Charged to Costs and Expenses	50	29	67
Deductions from Reserves	16	69	67
Balance at End of Period	$ 196	$ 162	$ 202