Investment In BBEP (Narrative) (Details) (USD $) In Thousands, except Share data, unless otherwise specified	9 Months Ended		1 Months Ended	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2010	Feb. 28, 2011 BBEP [Member]	Sep. 30, 2011 BBEP [Member]
Additional working interest				13.60%
Closing price of BBEP	17.40
Common units of investee disposed, units				7,700,000
Common units of investee owned, units				8,000,000
Commons units issued by investee			4,900,000
Weighted Average Unit Sales Price				$ 18.99
Weighted Average Carrying Value	$ 1.63
Gain on sale and disposition of BBEP units	$ 133,248	$ 49,850