Investments In Unconsolidated Affiliates (Details Textual) (USD $)	3 Months Ended	9 Months Ended
	Sep. 30, 2011	Sep. 30, 2011
Bighorn [Member]
Schedule of Equity Method Investments (Textual) [Abstract]
Investment	$ 214,030,000	$ 214,030,000
Non cash impairment charge	120,000,000
Fort Union Gas Gathering [Member]
Schedule of Equity Method Investments (Textual) [Abstract]
Condition for distribute cash to members		only if its ratio of net operating cash flow to debt service is not less than 1.25 to 1.00 and it is not otherwise in default under its credit agreement.
Non cash impairment charge	45,000,000
Fort Union [Member]
Schedule of Equity Method Investments (Textual) [Abstract]
Investment	169,169,000	169,169,000
Eagle Ford Gathering LLC ("Eagle Ford Gathering") [Member]
Schedule of Equity Method Investments (Textual) [Abstract]
Investment	$ 108,195,000	$ 108,195,000