Nuclear Decommissioning Trust (Details) (USD $)	3 Months Ended		9 Months Ended
	Sep. 30, 2012	Sep. 30, 2011	Sep. 30, 2012	Sep. 30, 2011	Dec. 31, 2011
Nuclear decommissioning trust fund assets
Fair Value	$ 566,960,000		$ 566,960,000		$ 513,733,000
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Proceeds from the sale of securities			295,126,000	405,637,000
Fair value of fixed income securities, summarized by contractual maturities
Total	566,960,000		566,960,000		513,733,000
ARIZONA PUBLIC SERVICE COMPANY
Nuclear decommissioning trust fund assets
Fair Value	566,960,000		566,960,000		513,733,000
Unrealized Gains	95,000,000		95,000,000		67,000,000
Unrealized Losses					(2,000,000)
Net payables for securities purchases	(3,000,000)		(3,000,000)		(1,000,000)
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	1,000,000	3,000,000	5,000,000	6,000,000
Realized losses	(1,000,000)	(1,000,000)	(3,000,000)	(4,000,000)
Proceeds from the sale of securities	84,000,000	106,000,000	295,126,000	405,637,000
Fair value of fixed income securities, summarized by contractual maturities
Total	566,960,000		566,960,000		513,733,000
ARIZONA PUBLIC SERVICE COMPANY | Equity Securities
Nuclear decommissioning trust fund assets
Fair Value	204,000,000		204,000,000		175,000,000
Unrealized Gains	68,000,000		68,000,000		44,000,000
Unrealized Losses					(1,000,000)
Fair value of fixed income securities, summarized by contractual maturities
Total	204,000,000		204,000,000		175,000,000
ARIZONA PUBLIC SERVICE COMPANY | Fixed income securities.
Nuclear decommissioning trust fund assets
Fair Value	366,000,000		366,000,000		340,000,000
Unrealized Gains	27,000,000		27,000,000		23,000,000
Unrealized Losses					(1,000,000)
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	22,000,000		22,000,000
1 year - 5 years	94,000,000		94,000,000
5 years - 10 years	103,000,000		103,000,000
Greater than 10 years	147,000,000		147,000,000
Total	$ 366,000,000		$ 366,000,000		$ 340,000,000