Supplemental Cash Flows Information (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Mar. 31, 2012	Mar. 31, 2011
Cash payments (receipts) for interest and taxes:
Interest - net of amounts capitalized	$ 157	$ 155
Tax payments (refunds) - net	(3)	(45)
Dividends declared but not paid:
Common stock	106	104
Preferred and preference stock	10	10
Noncash investing and financing activities:
Accrued capital expenditures	$ 419	$ 461