Supplemental Informaton on Oil and Gas Producing Activities (Details) (KMP [Member], USD $) In Millions, unless otherwise specified	12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010
KMP [Member]
Gas and Oil Acreage [Line Items]
Equity Method Investment, Ownership Percentage	30.80%
Equity Method Investment, Summarized Financial Information, Gross Profit (Loss)	$ 2,340	$ 1,557	$ 1,460