Acquisitions (Summary Of Fair Value Of Assets Acquired And Liabilities Assumed For 2012 East Texas Acquisition) (Details) (2012 East Texas Properties [Member], USD $)	0 Months Ended
	Dec. 04, 2012
2012 East Texas Properties [Member]
Business Acquisition [Line Items]
Evaluated	$ 218,039,000
Unevaluated	5,400,000
Other assets	1,900,000
Asset retirement obligation	(9,843,000)
Other current liabilities	(1,190,000)
Net assets (liabilities) acquired	214,306,000
Aggregate purchase price	$ 214,300,000