Nuclear Decommissioning Trusts (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013
Nuclear decommissioning trust fund assets
Fair Value	$ 690,226,000		$ 690,226,000		$ 642,007,000
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Proceeds from the sale of securities			269,276,000	363,944,000
Fair value of fixed income securities, summarized by contractual maturities
Total	690,226,000		690,226,000		642,007,000
Arizona Public Service Company
Nuclear decommissioning trust fund assets
Fair Value	690,226,000		690,226,000		642,007,000
Unrealized Gains	162,000,000		162,000,000		140,000,000
Unrealized Losses	(2,000,000)		(2,000,000)		(6,000,000)
Net payables for securities purchases	(2,000,000)		(2,000,000)		(3,000,000)
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	2,000,000	1,000,000	4,000,000	4,000,000
Realized losses	(2,000,000)	(3,000,000)	(5,000,000)	(5,000,000)
Proceeds from the sale of securities	70,000,000	110,000,000	269,276,000	363,944,000
Fair value of fixed income securities, summarized by contractual maturities
Total	690,226,000		690,226,000		642,007,000
Arizona Public Service Company | Equity Securities
Nuclear decommissioning trust fund assets
Fair Value	295,000,000		295,000,000		272,000,000
Unrealized Gains	147,000,000		147,000,000		129,000,000
Fair value of fixed income securities, summarized by contractual maturities
Total	295,000,000		295,000,000		272,000,000
Arizona Public Service Company | Fixed income securities.
Nuclear decommissioning trust fund assets
Fair Value	397,000,000		397,000,000		373,000,000
Unrealized Gains	15,000,000		15,000,000		11,000,000
Unrealized Losses	(2,000,000)		(2,000,000)		(6,000,000)
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	15,000,000		15,000,000
1 year - 5 years	121,000,000		121,000,000
5 years - 10 years	115,000,000		115,000,000
Greater than 10 years	146,000,000		146,000,000
Total	$ 397,000,000		$ 397,000,000		$ 373,000,000