Investments Narrative (Details) (USD $)	3 Months Ended		9 Months Ended							3 Months Ended	6 Months Ended	9 Months Ended		9 Months Ended
	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013	Sep. 30, 2012	Sep. 30, 2013 Frac Tech Holdings, L.L.C.	Sep. 30, 2013 Chaparral Energy, Inc.	Sep. 30, 2013 Sundrop Fuels, Inc.	Sep. 30, 2013 Twin Eagle Resources Management, LLC	Sep. 30, 2013 Maalt Specialized Bulk, LLC	Sep. 30, 2013 Clean Energy Fuels Corp.	Jun. 30, 2013 Clean Energy Fuels Corp.	Sep. 30, 2013 Clean Energy Fuels Corp.	Dec. 31, 2012 Clean Energy Fuels Corp.	Sep. 30, 2013 Gastar Exploration Ltd.	Sep. 30, 2013 Other Investments
Schedule of Equity Method Investments [Line Items]
Cost method percentage approximate owned										0.00%		0.00%
Other Commitment, Due in Next Twelve Months					$ 3,000,000
Positive equity method adjustments					17,000,000	11,000,000	14,000,000	4,000,000	0
Equity method accretion adjustments					34,000,000
Excess carrying value of investment over underlying equity in net assets					333,000,000	49,000,000	53,000,000
Equity Method Investment, Difference Between Carrying Amount and Underlying Equity Attributable to Goodwill					31,000,000
Goodwill, Not Allocated, Amount					265,000,000
Property, Plant and Equipment, Useful Life					P9Y
Depreciation						4,000,000
Equity method depreciation adjustments						3,000,000
Sale of Stock, Consideration Received on Transaction												13,000,000		10,000,000	6,000,000
Impairment of investment	0	0	10,000,000	0						15,000,000
Cost Method Investments										0		0	100,000,000
Proceeds from Cost Method Investment											85,000,000
Other Commitment	50,000,000		50,000,000							50,000,000		50,000,000
Gains (losses) on sales of investments										$ 3,000,000					$ 5,000,000