Debt, Accounts Receivable Sales Facility and Capitalized Interest (Details) (USD $)	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Capitalized Interest (Textual)
Interest costs incurred, capitalized	$ 70,000,000	$ 118,000,000	$ 220,000,000
A/R Sales Facility [Member]
Accounts Receivable Sales Facility
Balance as of beginning of year				250,000,000
Balance as of end of year	100,000,000	100,000,000	100,000,000	250,000,000
Credit Facilities [Member] | A/R Sales Facility [Member]
Accounts Receivable Sales Facility
Proceeds from the sale of receivables	0	0	1,500,000,000
Repayments	0	0	(1,650,000,000)
Accounts Receivable Sales Facility (Textual)
Line of credit facility, maximum borrowing capacity	1,500,000,000
Extended term of accounts receivable sales facility	Jul. 31, 2015
Designated pool of accounts receivable	$ 1,700,000,000	$ 3,300,000,000