Debt and Equity Transactions (Unaudited) Interests and Dividends (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011	Feb. 07, 2012
Class of Stock [Line Items]
Interest costs incurred	$ 55	$ 97	$ 154	$ 220
Interest costs capitalized	$ 12	$ 23	$ 48	$ 48
Annual Cash Dividend Before Increase					$ 1.00
Annual Cash Dividend Current					$ 1.25
Dividends Payable, Amount Per Share (in dollars per share)	$ 0.3125		$ 0.3125
Dividends Payable, Date Declared	Jun. 27, 2012
Dividends Payable, Date to be Paid	Aug. 01, 2012
Dividends Payable, Date of Record	Jul. 13, 2012