Derivative Accounting Narrative (Details) (USD $)	3 Months Ended
	Mar. 31, 2015 Counterparty	Mar. 31, 2014	Dec. 31, 2014
Derivative Accounting
Percentage of deferred unrealized gains (losses) on contracts due to PSA recovery	100.00%
Arizona Public Service Company
Derivative Accounting
Percentage of unrealized gains and losses on certain derivatives deferred for future rate treatment	100.00%
Designated as Hedging Instruments
Derivative Accounting
Gross recognized derivatives	$ 4,000,000		$ 4,000,000
Commodity Contracts
Derivative Accounting
Gross recognized derivatives	203,980,000		169,052,000
Amounts offset	(56,900,000)		(43,900,000)
Derivative liability, not subject to master netting arrangement	7,023,000		7,443,000
Other	626,000		350,000
Concentration of credit risk, number of counterparties	1
Concentration of risk with two counterparties, as a percentage of risk management assets	94.00%
Risk management activities-derivative instruments: Commodity Contracts	32,102,000		31,405,000
Additional collateral to counterparties for energy related non-derivative instrument contracts	166,000,000
Commodity Contracts | Designated as Hedging Instruments
Derivative Accounting
Amount reclassified from accumulated other comprehensive income to earnings related to discontinued cash flow hedges	0	0
Estimated net gain (loss) before income taxes to be reclassified from accumulated other comprehensive income	(5,000,000)
Current Liabilities | Commodity Contracts
Derivative Accounting
Gross recognized derivatives	97,349,000		86,062,000
Amounts offset	(56,900,000)		(43,900,000)
Derivative liability, not subject to master netting arrangement	$ 7,023,000		$ 7,443,000