Accounting For Asset Retirement Obligations (Change In Estimated Probabilities Due) (Details)	6 Months Ended
	Jun. 30, 2011
Original ARO Liability [Member]
Asset Retirement Obligation Escalation Rate	3.60%
Asset Retirement Obligation Discount Rate	9.50%
Incremental ARO Liability [Member]
Asset Retirement Obligation Escalation Rate	3.60%
Asset Retirement Obligation Discount Rate	6.20%