Debt and Equity Transactions (Unaudited) Interests and Dividends (Details) (USD $) In Millions, except Per Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011	Feb. 07, 2012
Class of Stock [Line Items]
Interest costs incurred	$ 99	$ 123
Interest costs capitalized	$ 36	$ 25
Annual Cash Dividend Before Increase			$ 1.00
Annual Cash Dividend Current			$ 1.25
Dividends Payable, Amount Per Share (in dollars per share)	$ 0.3125
Dividends Payable, Date Declared, Day, Month and Year	Mar. 28, 2012
Dividends Payable, Date to be Paid, Day, Month and Year	May 01, 2012
Dividends Payable, Date of Record, Day, Month and Year	Apr. 13, 2012