Derivative Accounting - Outstanding Gross Notional Amounts Outstanding (Details)	Dec. 31, 2014 GW
Commodity - Power
Outstanding gross notional amount of derivatives
Outstanding gross notional amount of derivative instruments	3,915
Commodity - Gas
Outstanding gross notional amount of derivatives
Outstanding gross notional amount of derivative instruments	136,000

Aggregate notional amount of price risk derivatives designated as a cash flow hedge with a notional amounts expressed in nonmonetary units. For example the number of barrels specified in a fuel oil forward purchase contract.

No definition available.

Name:	pnw_NonmonetaryNotionalAmountOfPriceRiskCashFlowHedgeDerivatives2
Namespace Prefix:	pnw_
Data Type:	num:volumeItemType
Balance Type:	na
Period Type:	instant