Investments Narrative (Details) (USD $) In Millions, except Share data, unless otherwise specified	12 Months Ended					1 Months Ended	12 Months Ended	1 Months Ended		12 Months Ended		12 Months Ended		1 Months Ended		12 Months Ended			12 Months Ended
	Dec. 31, 2012	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2012 Frac Tech Holdings, L.L.C.	Dec. 31, 2012 Chaparral Energy, Inc.	Jul. 31, 2011 Sundrop Fuels, Inc. gal	Dec. 31, 2012 Sundrop Fuels, Inc.	Dec. 31, 2011 Clean Energy Fuels Corp.	Jul. 31, 2011 Clean Energy Fuels Corp.	Dec. 31, 2012 Clean Energy Fuels Corp.	Jul. 11, 2011 Clean Energy Fuels Corp.	Dec. 31, 2012 Twin Eagle Resources Management, LLC	Dec. 31, 2010 Twin Eagle Resources Management, LLC	Dec. 31, 2011 Gastar Exploration Ltd.	Mar. 31, 2009 Gastar Exploration Ltd.	Dec. 31, 2012 Gastar Exploration Ltd.	Dec. 31, 2012 Chesapeake Midstream Partners, L.P.	Apr. 30, 2012 Glass Mountain Pipeline Limited Liability Company mi	Dec. 31, 2012 Maalt Specialized Bulk, LLC
Schedule of Equity Method Investments [Line Items]
Positive equity method adjustments				$ 91	$ 4		$ 3					$ 5					$ 46
Equity method accretion adjustments				45													4
Equity Investment Additional Payment				3
Excess carrying value of investment over underlying equity in net assets				622	52		53
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity Attributable to Goodwill				296
Goodwill, Not Allocated, Amount				200
Property, Plant and Equipment, Useful Life				P9Y
Other Commitment, Due in Next Twelve Months				106
Depreciation					3
Equity method depreciation adjustments					3
Investment in preferred stock						155	115
Expected production of gallons of gasoline from natural gas and waste cellulosic						40,000,000
Equity Method Investment, Permiums Paid							80
Equity Method Investment, Ownership Percentage					20.00%	50.00%	50.00%					30.00%						50.00%	49.00%
Investment in newly issued convertible notes									150	50	50
Annual interest rate on notes									7.50%
Conversion premium of convertible option into shares									22.50%
Conversion price for convertible promissory note									$ 15.80
Shares purchased								1,000,000
Cost of investment								10								89
Maximum common stock price per share								$ 12.46						$ 3.18
Minimum common stock price per share										$ 12.45						$ 1.21
Equity Method Investment, Other than Temporary Impairment															70
Income (Loss) from Equity Method Investments	164	(41)	(107)							2						11
Equity method investment												19	20						12
Proceeds from Sale of Equity Method Investments	2,000	0	0
Payments to Acquire Equity Method Investments																			1
Deferred gain realized related to previously sold equipment to ACMP																	13
Gain on sale of equity method investment																	1,032
Cash distribution from the equity investment																	56
Additional assets sold, miles of pipeline																		210
Sale of Investment																		99
Gain on Sale of Investment																		$ 62