Accounting For Asset Retirement Obligations (Change In Estimated Probabilities Due) (Details)	9 Months Ended
	Sep. 30, 2011
Original ARO Liability [Member]
ARO Escalation Rate	3.60%
ARO Credit-Risk Adjusted Discount Rate	9.50%
Incremental ARO Liability [Member]
ARO Escalation Rate	3.60%
ARO Credit-Risk Adjusted Discount Rate	6.20%