Nuclear Decommissioning Trusts (Details) - USD ($) $ in Thousands	3 Months Ended		9 Months Ended
	Sep. 30, 2015	Sep. 30, 2014	Sep. 30, 2015	Sep. 30, 2014	Dec. 31, 2014
Nuclear decommissioning trust fund assets
Fair Value	$ 712,011		$ 712,011		$ 713,866
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Proceeds from the sale of securities			330,304	$ 269,276
Fair value of fixed income securities, summarized by contractual maturities
Total	712,011		712,011		713,866
Arizona Public Service Company
Nuclear decommissioning trust fund assets
Fair Value	712,011		712,011		713,866
Unrealized Gains	153,000		153,000		176,000
Unrealized Losses	(4,000)		(4,000)		(1,000)
Net payables for securities purchases					(7,000)
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	2,000	$ 2,000	4,000	4,000
Realized losses	(2,000)	(2,000)	(4,000)	(5,000)
Proceeds from the sale of securities	105,000	$ 70,000	330,304	$ 269,276
Fair value of fixed income securities, summarized by contractual maturities
Total	712,011		712,011		713,866
Arizona Public Service Company | Equity Securities
Nuclear decommissioning trust fund assets
Fair Value	294,000		294,000		310,000
Unrealized Gains	138,000		138,000		159,000
Unrealized Losses	(1,000)		(1,000)
Fair value of fixed income securities, summarized by contractual maturities
Total	294,000		294,000		310,000
Arizona Public Service Company | Fixed income securities.
Nuclear decommissioning trust fund assets
Fair Value	418,000		418,000		411,000
Unrealized Gains	15,000		15,000		17,000
Unrealized Losses	(3,000)		(3,000)		(1,000)
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	15,000		15,000
1 year - 5 years	117,000		117,000
5 years - 10 years	117,000		117,000
Greater than 10 years	169,000		169,000
Total	$ 418,000		$ 418,000		$ 411,000