Nuclear Decommissioning Trusts (Details) (USD $)	3 Months Ended
	Mar. 31, 2015	Mar. 31, 2014	Dec. 31, 2014
Nuclear decommissioning trust fund assets
Fair Value	$ 727,342,000		$ 713,866,000
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Proceeds from the sale of securities	115,282,000	103,157,000
Fair value of fixed income securities, summarized by contractual maturities
Total	727,342,000		713,866,000
Arizona Public Service Company
Nuclear decommissioning trust fund assets
Fair Value	727,342,000		713,866,000
Unrealized Gains	181,000,000		176,000,000
Unrealized Losses	(1,000,000)		(1,000,000)
Net payables for securities purchases	(2,000,000)		(7,000,000)
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	1,000,000	1,000,000
Realized losses	(1,000,000)	(2,000,000)
Proceeds from the sale of securities	115,282,000	103,157,000
Fair value of fixed income securities, summarized by contractual maturities
Total	727,342,000		713,866,000
Arizona Public Service Company | Equity Securities
Nuclear decommissioning trust fund assets
Fair Value	313,000,000		310,000,000
Unrealized Gains	161,000,000		159,000,000
Fair value of fixed income securities, summarized by contractual maturities
Total	313,000,000		310,000,000
Arizona Public Service Company | Fixed income securities.
Nuclear decommissioning trust fund assets
Fair Value	416,000,000		411,000,000
Unrealized Gains	20,000,000		17,000,000
Unrealized Losses	(1,000,000)		(1,000,000)
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	16,000,000
1 year - 5 years	113,000,000
5 years - 10 years	118,000,000
Greater than 10 years	169,000,000
Total	$ 416,000,000		$ 411,000,000