Accounting for Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2016

Accounting for Asset Retirement Obligations

Changes In Estimated Probabilities Assumptions

The assumptions used to calculate the Palo Verde 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	%

Schedule of Asset Retirement Obligations

	2016			2015		2014
ARO liability at beginning of year	$	81,621		$	74,577	$	65,214
Liabilities incurred	—			189		—
Liabilities settled	(6,993		)	—		—
Revisions to estimate	—			—		3,561
Accretion expense	7,172			6,855		5,802
ARO liability at end of year	$	81,800		$	81,621	$	74,577