Accounting For Asset Retirement Obligations (Tables)

9 Months Ended

Sep. 30, 2011

Asset Retirement Obligation [Abstract]

Changes In Estimated Probabilities Assumptions [Table Text Block]

The assumptions used to calculate the original ARO liability and the revised ARO liability are as follows:

	Escalation Rate	Credit-Risk Adjusted Discount Rate
Original ARO liability	3.60%	9.50%
Incremental ARO liability	3.60%	6.20%

Rollforward Of ARO Liability Recorded

A roll forward of the Company’s ARO liability is presented below and revisions to estimates include both the increase to estimated cash flows and the change in estimated probabilities due to Palo Verde license extension.

	2011			2010
	(in thousands)
ARO liability at beginning of year	$	92,911		$	85,358
Revisions to estimates	(41,670		)	—
Accretion expense	4,499			5,942
Liabilities settled	(796		)	(357		)
ARO liability at September 30	$	54,944		$	90,943