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The fair value of investments held in a trust fund to pay for the costs of decontaminating and decommissioning facilities, whether such amount is presented as a separate caption or as a parenthetical disclosure on the balance sheet. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements.

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Nuclear Decommissioning Trust (Details) (USD $)	3 Months Ended		9 Months Ended
Nuclear Decommissioning Trust (Details) (USD $)	Sep. 30, 2011	Sep. 30, 2010	Sep. 30, 2011	Sep. 30, 2010	Dec. 31, 2010
Nuclear decommissioning trust fund assets
Fair Value	$ 488,551,000		$ 488,551,000		$ 469,886,000
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Proceeds from the sale of securities			405,637,000	424,255,000
Fair value of fixed income securities, summarized by contractual maturities
Total	488,551,000		488,551,000		469,886,000
ARIZONA PUBLIC SERVICE COMPANY
Nuclear decommissioning trust fund assets
Fair Value	488,551,000		488,551,000		469,886,000
Total Unrealized Gains	54,000,000		54,000,000		55,000,000
Total Unrealized Losses	(6,000,000)		(6,000,000)		(3,000,000)
Net receivables from securities sales	2,000,000		2,000,000
Net payables from securities purchases					(10,000,000)
Realized gains and losses and proceeds from the sale of securities by the nuclear decommissioning trust funds
Realized gains	3,000,000	1,000,000	6,000,000	15,000,000
Realized losses	(1,000,000)		(4,000,000)	(3,000,000)
Proceeds from the sale of securities	106,000,000	94,000,000	405,637,000	424,255,000
Fair value of fixed income securities, summarized by contractual maturities
Total	488,551,000		488,551,000		469,886,000
ARIZONA PUBLIC SERVICE COMPANY \| Equity securities
Nuclear decommissioning trust fund assets
Fair Value	154,000,000		154,000,000		168,000,000
Total Unrealized Gains	31,000,000		31,000,000		43,000,000
Total Unrealized Losses	(5,000,000)		(5,000,000)		(1,000,000)
Fair value of fixed income securities, summarized by contractual maturities
Total	154,000,000		154,000,000		168,000,000
ARIZONA PUBLIC SERVICE COMPANY \| Fixed income securities.
Nuclear decommissioning trust fund assets
Fair Value	333,000,000		333,000,000		312,000,000
Total Unrealized Gains	23,000,000		23,000,000		12,000,000
Total Unrealized Losses	(1,000,000)		(1,000,000)		(2,000,000)
Fair value of fixed income securities, summarized by contractual maturities
Less than one year	16,000,000		16,000,000
1 year - 5 years	78,000,000		78,000,000
5 years - 10 years	114,000,000		114,000,000
Greater than 10 years	125,000,000		125,000,000
Total	$ 333,000,000		$ 333,000,000		$ 312,000,000