Asset Acquisition (Details Textuals) (Clearfield Energy [Member], USD $) In Thousands, unless otherwise specified	9 Months Ended
	Sep. 30, 2012	Jul. 02, 2012
Clearfield Energy [Member]
Business Acquisition [Line Items]
Business Acquisition, Date of Acquisition Agreement	Jul. 02, 2012
Business Acquisition, Name of Acquired Entity	Clearfield Energy, Inc.
Business Acquisition, Cost of Acquired Entity, Cash Paid	$ 212,521
Acquired Finite-lived Intangible Assets, Weighted Average Useful Life	20 years
Right Of Way Option Life	10 years
Business Acquisition, Purchase Price Allocation, Deferred Tax		67,700
"LDC" assets held for sale		$ 19,500