Debt, Accounts Receivable Sales Facility and Capitalized Interest (Details) (USD $)	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Jul. 31, 2012	Jun. 30, 2012
Accounts Receivable Sales Facility
Proceeds from the sale of receivables	$ 1,500,000,000	$ 150,000,000	$ 1,225,000,000
Repayments	(1,650,000,000)	0	(1,325,000,000)
Capitalized Interest (Textual)
Interest costs incurred, capitalized	221,000,000	152,000,000	90,000,000
Other Debt [Member]
Accounts Receivable Sales Facility
Balance as of beginning of year	250,000,000	100,000,000	200,000,000
Proceeds from the sale of receivables	1,500,000,000	150,000,000	1,225,000,000
Repayments	(1,650,000,000)	0	(1,325,000,000)
Balance as of end of year	100,000,000	250,000,000	100,000,000
Accounts Receivable Sales Facility (Textual)
Maximum eligible trade receivables				1,500,000,000	1,000,000,000
Extended term of accounts receivable sales facility	July 2013
Designated pool of accounts receivable	$ 3,200,000,000	$ 3,300,000,000