Regulatory Matters (Tables)

3 Months Ended

Mar. 31, 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):

	Three Months Ended   March 31,
	2017		2016
Beginning balance	$	12,465	$	(9,688	)
Deferred fuel and purchased power costs — current period	988		(1,007		)
Amounts charged to customers	4,172		(2,388		)
Ending balance	$	17,625	$	(13,083	)

Schedule of regulatory assets

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

	Amortization Through	March 31, 2017				December 31, 2016
		Current		Non-Current		Current		Non-Current
Pension	(a)	$	—	$	699,817	$	—	$	711,059
Retired power plant costs	2033	9,913		115,110		9,913		117,591
Income taxes — allowance for funds used during construction ("AFUDC") equity	2047	6,202		150,629		6,305		152,118
Deferred fuel and purchased power — mark-to-market (Note 6)	2020	30,203		59,428		—		42,963
Deferred fuel and purchased power (b) (e)	2018	17,625		—		12,465		—
Four Corners cost deferral	2024	6,689		55,221		6,689		56,894
Income taxes — investment tax credit basis adjustment	2046	2,120		54,265		2,120		54,356
Lost fixed cost recovery (b)	2018	70,762		—		61,307		—
Palo Verde VIEs (Note 5)	2046	—		18,930		—		18,775
Deferred compensation	2036	—		36,846		—		35,595
Deferred property taxes	(c)	—		79,447		—		73,200
Loss on reacquired debt	2038	1,637		16,533		1,637		16,942
Tax expense of Medicare subsidy	2024	1,503		10,458		1,513		10,589
Demand Side Management	2018	5,491		—		3,744		—
AG-1 deferral	2018	—		6,976		—		5,868
Mead-Phoenix transmission line CIAC	2050	332		10,625		332		10,708
Transmission cost adjustor (b)	2018	2,071		2,460		—		1,588
Coal reclamation	2026	418		4,728		418		5,182
Other	Various	975		—		432		—
Total regulatory assets (d)		$	155,941	$	1,321,473	$	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.

Schedule of regulatory liabilities

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

	Amortization Through	March 31, 2017				December 31, 2016
		Current		Non-Current		Current		Non-Current
Asset retirement obligations	2057	$	—	$	298,796	$	—	$	279,976
Removal costs	(a)	37,194		211,348		29,899		223,145
Other postretirement benefits	(c)	32,662		115,950		32,662		123,913
Income taxes — deferred investment tax credit	2046	4,315		108,691		4,368		108,827
Income taxes — change in rates	2046	2,565		69,497		1,771		70,898
Spent nuclear fuel	2047	—		72,755		—		71,726
Renewable energy standard (b)	2018	22,367		—		26,809		—
Demand side management (b)	2019	—		19,921		—		20,472
Sundance maintenance	2030	—		15,690		—		15,287
Deferred gains on utility property	2019	2,062		8,439		2,063		8,895
Four Corners coal reclamation	2031	—		19,684		—		18,248
Other	Various	43		7,522		2,327		7,529
Total regulatory liabilities		$	101,208	$	948,293	$	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 "Cost Recovery Mechanisms" discussion above.

(c) See Note 4.