Debt, Accounts Receivable Sales Facility and Capitalized Interest (Details) (USD $) In Millions, unless otherwise specified	1 Months Ended	12 Months Ended
	Jun. 30, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Accounts Receivable Sales Facility
Proceeds from the sale of receivables		$ 150	$ 1,225	$ 950
Repayments		0	(1,325)	(850)
Accounts Receivable Sales Facility (Textual)
Maximum eligible trade receivables		1,000
Extended term of accounts receivable sales facility	June 2012
Capitalized Interest (Textual)
Interest costs incurred, capitalized		152	90	105
Other Debt [Member]
Accounts Receivable Sales Facility
Balance as of beginning of year		100	200	100
Proceeds from the sale of receivables		150	1,225	950
Repayments		0	(1,325)	(850)
Balance as of end of year		250	100	200
Accounts Receivable Sales Facility (Textual)
Designated pool of accounts receivable		$ 3,300	$ 2,200