Nuclear Decommissioning Trusts (Details) - USD ($) $ in Thousands	3 Months Ended		6 Months Ended
	Jun. 30, 2015	Jun. 30, 2014	Jun. 30, 2015	Jun. 30, 2014	Dec. 31, 2014
Nuclear decommissioning trust fund assets
Fair Value	$ 723,582		$ 723,582		$ 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			225,779	$ 199,224
Fair value of fixed income securities, summarized by contractual maturities
Total	723,582		723,582		713,866
Arizona Public Service Company
Nuclear decommissioning trust fund assets
Fair Value	723,582		723,582		713,866
Unrealized Gains	173,000		173,000		176,000
Unrealized Losses	(3,000)		(3,000)		(1,000)
Net payables for securities purchases	(4,000)		(4,000)		(7,000)
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	1,000	$ 1,000	2,000	2,000
Realized losses	(1,000)	(1,000)	(2,000)	(3,000)
Proceeds from the sale of securities	110,000	$ 96,000	225,779	$ 199,224
Fair value of fixed income securities, summarized by contractual maturities
Total	723,582		723,582		713,866
Arizona Public Service Company | Equity Securities
Nuclear decommissioning trust fund assets
Fair Value	314,000		314,000		310,000
Unrealized Gains	160,000		160,000		159,000
Fair value of fixed income securities, summarized by contractual maturities
Total	314,000		314,000		310,000
Arizona Public Service Company | Fixed income securities.
Nuclear decommissioning trust fund assets
Fair Value	414,000		414,000		411,000
Unrealized Gains	13,000		13,000		17,000
Unrealized Losses	(3,000)		(3,000)		(1,000)
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	13,000		13,000
1 year - 5 years	111,000		111,000
5 years - 10 years	123,000		123,000
Greater than 10 years	167,000		167,000
Total	$ 414,000		$ 414,000		$ 411,000