Summary of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2017

Accounting Policies [Abstract]

Schedule of reclassifications of the prior year

The following tables show the impacts of the reclassifications of the prior year (previously reported) amounts (dollars in thousands):

Pinnacle West Capital Corporation Consolidated Balance Sheets- December 31, 2016	As previously reported			Reclassifications to conform to current year presentation			Amount reported after reclassification to conform to current year presentation
Accumulated other comprehensive loss:
Pension and other postretirement benefits	$	(39,070	)	$	39,070		$	—
Derivative instruments	(4,752		)	4,752			—
Total accumulated other comprehensive loss	(43,822		)	43,822			—
Accumulated other comprehensive loss	—			(43,822		)	(43,822		)

Arizona Public Service Company Consolidated Balance Sheets - December 31, 2016	As previously reported			Reclassifications to conform to current year presentation			Amount reported after reclassification to conform to current year presentation
Accumulated other comprehensive loss:
Pension and other postretirement benefits	$	(20,671	)	$	20,671		$	—
Derivative instruments	(4,752		)	4,752			—
Total accumulated other comprehensive loss	(25,423		)	25,423			—
Accumulated other comprehensive loss	—			(25,423		)	(25,423		)

Schedule of property, plant and equipment

Pinnacle West’s property, plant and equipment included in the December 31, 2017 and 2016 Consolidated Balance Sheets is composed of the following (dollars in thousands):

Property, Plant and Equipment:	2017			2016
Generation	$	7,963,998		$	7,874,898
Transmission	2,836,578			2,746,508
Distribution	6,025,856			5,738,801
General plant	971,629			981,681
Plant in service and held for future use	17,798,061			17,341,888
Accumulated depreciation and amortization	(6,128,535		)	(5,970,100		)
Net	11,669,526			11,371,788
Construction work in progress	1,291,498			1,019,947
Palo Verde sale leaseback, net of accumulated depreciation	109,645			113,515
Intangible assets, net of accumulated amortization	257,189			90,022
Nuclear fuel, net of accumulated amortization	117,408			119,004
Total property, plant and equipment	$	13,445,266		$	12,714,276

Summary of supplemental cash flow information

The following table summarizes supplemental Pinnacle West cash flow information for each of the last three years (dollars in thousands):

	Year ended December 31,
	2017		2016		2015
Cash paid during the period for:
Income taxes, net of refunds	$	2,186	$	9,956	$	6,550
Interest, net of amounts capitalized	189,288		184,462		170,209
Significant non-cash investing and financing activities:
Accrued capital expenditures	$	130,404	$	114,855	$	83,798
Dividends declared but not paid	77,667		72,926		69,363