CONDENSED CONSOLIDATED STATEMENTS OF CHANGES IN EQUITY (Unaudited) - USD ($) $ in Thousands		Total	Common Stock	Treasury Stock	Retained Earnings	Accumulated Other Comprehensive Income (Loss)	Noncontrolling Interests	Arizona Public Service Company	Arizona Public Service Company Common Stock	Arizona Public Service Company Additional Paid-In Capital	Arizona Public Service Company Retained Earnings	Arizona Public Service Company Accumulated Other Comprehensive Income (Loss)	Arizona Public Service Company Noncontrolling Interests
Beginning balance (in shares) at Dec. 31, 2016			111,392,053	55,317					71,264,947
Balance at beginning of period at Dec. 31, 2016		$ 4,935,912	$ 2,596,030	$ (4,133)	$ 2,255,547	$ (43,822)	$ 132,290	$ 5,037,970	$ 178,162	$ 2,421,696	$ 2,331,245	$ (25,423)	$ 132,290
Increase (Decrease) in Shareholders' Equity
Net income		28,185			23,312		4,873	28,035			23,162		4,873
Other comprehensive income		959				959		1,048				1,048
Other		(1)									(2)		1
Issuance of common stock (in shares)			194,995
Issuance of common stock		(988)	$ (988)
Purchase of treasury stock (in shares)	[1]			(153,470)
Purchase of treasury stock	[1]	(12,141)		$ (12,141)
Reissuance of treasury stock for stock-based compensation and other (in shares)				179,592
Reissuance of treasury stock for stock-based compensation and other		14,013		$ 14,004	8		1
Ending balance (in shares) at Mar. 31, 2017			111,587,048	29,195					71,264,947
Balance at end of period at Mar. 31, 2017		$ 4,965,940	$ 2,595,042	$ (2,270)	2,278,867	(42,863)	137,164	5,067,052	$ 178,162	2,421,696	2,354,405	(24,375)	137,164
Beginning balance (in shares) at Dec. 31, 2017		111,816,170	111,816,170	64,463					71,264,947
Balance at beginning of period at Dec. 31, 2017		$ 5,135,730	$ 2,614,805	$ (5,624)	2,442,511	(45,002)	129,040	5,385,869	$ 178,162	2,571,696	2,533,954	(26,983)	129,040
Increase (Decrease) in Shareholders' Equity
Net income		8,094			3,221		4,873	14,472			9,599		4,873
Other comprehensive income		1,213				1,213		1,170				1,170
Other								1			0		1
Dividends on common stock		(16)			(16)
Issuance of common stock (in shares)			145,793
Issuance of common stock		5,456	$ 5,456
Purchase of treasury stock (in shares)	[1]			(81,177)
Purchase of treasury stock	[1]	(6,277)		$ (6,277)
Reissuance of treasury stock for stock-based compensation and other (in shares)				116,543
Reissuance of treasury stock for stock-based compensation and other		9,471		$ 9,470	0		1
Reclassification of income tax effects related to new tax reform (See Note 13)		$ 0			8,552	(8,552)					5,038	(5,038)
Ending balance (in shares) at Mar. 31, 2018		111,961,963	111,961,963	29,097					71,264,947.000
Balance at end of period at Mar. 31, 2018		$ 5,153,671	$ 2,620,261	$ (2,431)	$ 2,454,268	$ (52,341)	$ 133,914	$ 5,401,512	$ 178,162	$ 2,571,696	$ 2,548,591	$ (30,851)	$ 133,914

[1] Primarily represents shares of common stock withheld from certain stock awards for tax purposes.