Regulatory Matters (Tables)

6 Months Ended

Jun. 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):

	Six Months Ended   June 30,
	2017		2016
Beginning balance	$	12,465	$	(9,688	)
Deferred fuel and purchased power costs — current period	21,994		21,027
Amounts refunded/(charged) to customers	13,663		(13,778		)
Ending balance	$	48,122	$	(2,439	)

Schedule of regulatory assets

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

	Amortization Through	June 30, 2017				December 31, 2016
		Current		Non-Current		Current		Non-Current
Pension	(a)	$	—	$	697,184	$	—	$	711,059
Retired power plant costs	Various	19,083		205,418		9,913		117,591
Income taxes — allowance for funds used during construction ("AFUDC") equity	2047	6,202		158,356		6,305		152,118
Deferred fuel and purchased power — mark-to-market (Note 6)	2020	45,993		43,354		—		42,963
Deferred fuel and purchased power (b) (e)	2018	48,122		—		12,465		—
Four Corners cost deferral	2024	6,689		53,549		6,689		56,894
Income taxes — investment tax credit basis adjustment	2046	2,120		53,509		2,120		54,356
Lost fixed cost recovery (b)	2018	75,070		—		61,307		—
Palo Verde VIEs (Note 5)	2046	—		19,085		—		18,775
Deferred compensation	2036	—		37,161		—		35,595
Deferred property taxes	(c)	—		85,694		—		73,200
Loss on reacquired debt	2038	1,637		16,124		1,637		16,942
Tax expense of Medicare subsidy	2024	1,503		9,922		1,513		10,589
Demand Side Management	2018	5,122		—		3,744		—
AG-1 deferral	(f)	—		10,058		—		5,868
Mead-Phoenix transmission line CIAC	2050	332		10,542		332		10,708
Transmission cost adjustor (b)	2018	8,115		—		—		1,588
Coal reclamation	2026	418		15,135		418		5,182
Other	Various	322		—		432		—
Total regulatory assets (d)		$	220,728	$	1,415,091	$	106,875	$	1,313,428

(a) See Note 4 for further discussion.

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

(c) Per the provision of the 2012 Settlement Agreement.

(d) 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."

(e) Subject to a carrying charge.

(f) Amortization is expected through 2022, but the balance is classified as non-current since the related 2017 Settlement Agreement was not approved as of June 30, 2017.

Schedule of regulatory liabilities

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

	Amortization Through	June 30, 2017				December 31, 2016
		Current		Non-Current		Current		Non-Current
Asset retirement obligations	2057	$	—	$	321,732	$	—	$	279,976
Removal costs	(a)	37,943		189,959		29,899		223,145
Other postretirement benefits	(b)	32,725		107,764		32,662		123,913
Income taxes — deferred investment tax credit	2046	4,315		107,153		4,368		108,827
Income taxes — change in rates	2046	2,565		68,583		1,771		70,898
Spent nuclear fuel	2047	—		71,996		—		71,726
Renewable energy standard (c)	2018	11,519		—		26,809		—
Demand side management (c)	2019	—		19,921		—		20,472
Sundance maintenance	2030	—		16,092		—		15,287
Deferred gains on utility property	2019	2,063		7,851		2,063		8,895
Four Corners coal reclamation	2031	—		20,894		—		18,248
Other	Various	43		8,161		2,327		7,529
Total regulatory liabilities		$	91,173	$	940,106	$	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.