Regulatory Matters (Tables)

9 Months Ended

Sep. 30, 2017

Regulated Operations [Abstract]

Schedule of changes in the deferred fuel and purchased power regulatory asset

The following table shows the changes in the deferred fuel and purchased power regulatory asset (liability) for 2017 and 2016 (dollars in thousands):

	Nine Months Ended   September 30,
	2017		2016
Beginning balance	$	12,465	$	(9,688	)
Deferred fuel and purchased power costs — current period	43,348		46,185
Amounts refunded/(charged) to customers	18,153		(28,365		)
Ending balance	$	73,966	$	8,132

Schedule of regulatory assets

The detail of regulatory assets is as follows (dollars in thousands): 

	Amortization Through	September 30, 2017				December 31, 2016
		Current		Non-Current		Current		Non-Current
Pension	(a)	$	—	$	686,511	$	—	$	711,059
Retired power plant costs	Various	28,647		194,639		9,913		117,591
Income taxes — allowance for funds used during construction ("AFUDC") equity	2047	6,202		170,622		6,305		152,118
Deferred fuel and purchased power — mark-to-market (Note 6)	2020	45,463		33,115		—		42,963
Deferred fuel and purchased power (b) (d)	2018	73,966		—		12,465		—
Four Corners cost deferral	2024	8,077		50,324		6,689		56,894
Income taxes — investment tax credit basis adjustment	2046	2,120		53,225		2,120		54,356
Lost fixed cost recovery (b)	2018	67,500		—		61,307		—
Palo Verde VIEs (Note 5)	2046	—		19,240		—		18,775
Deferred compensation	2036	—		37,265		—		35,595
Deferred property taxes	2027	8,569		77,408		—		73,200
Loss on reacquired debt	2038	1,637		15,715		1,637		16,942
Tax expense of Medicare subsidy	2024	1,503		9,074		1,513		10,589
Demand Side Management	2018	—		—		3,744		—
AG-1 deferral	2022	2,654		9,136		—		5,868
Mead-Phoenix transmission line CIAC	2050	332		10,459		332		10,708
Transmission cost adjustor (b)	2018	4,345		—		—		1,588
Coal reclamation	2026	1,068		14,446		418		5,182
Other	Various	6,234		—		432		—
Total regulatory assets (c)		$	258,317	$	1,381,179	$	106,875	$	1,313,428

(a) See Note 4 for further discussion.

(b) See "Cost Recovery Mechanisms" discussion above.

(c) There are no regulatory assets for which the ACC has allowed recovery of costs, but not allowed a return by exclusion from rate base.  FERC rates are set using a formula rate as described in "Transmission Rates, Transmission Cost Adjustor and Other Transmission Matters."

(d) Subject to a carrying charge.

Schedule of regulatory liabilities

The detail of regulatory liabilities is as follows (dollars in thousands):

	Amortization Through	September 30, 2017				December 31, 2016
		Current		Non-Current		Current		Non-Current
Asset retirement obligations	2057	$	—	$	313,189	$	—	$	279,976
Removal costs	(a)	37,756		184,512		29,899		223,145
Other postretirement benefits	(b)	32,725		99,626		32,662		123,913
Income taxes — deferred investment tax credit	2046	4,315		106,557		4,368		108,827
Income taxes — change in rates	2046	2,565		67,136		1,771		70,898
Spent nuclear fuel	2027	6,562		64,504		—		71,726
Renewable energy standard (c)	2018	17,915		—		26,809		—
Demand side management (c)	2019	12,175		4,921		—		20,472
Sundance maintenance	2030	—		16,494		—		15,287
Deferred gains on utility property	2022	4,525		11,875		2,063		8,895
Four Corners coal reclamation	2031	1,857		19,494		—		18,248
Other	Various	276		3,407		2,327		7,529
Total regulatory liabilities		$	120,671	$	891,715	$	99,899	$	948,916

(a) In accordance with regulatory accounting guidance, APS accrues for removal costs for its regulated assets, even if there is no legal obligation for removal.

(b) See Note 4 for further discussion.

(c) See "Cost Recovery Mechanisms" discussion above.