Retirement Plans and Other Benefits (Details 3) (USD $) In Thousands, unless otherwise specified													12 Months Ended																		12 Months Ended																																		12 Months Ended									12 Months Ended
	Dec. 31, 2012 Pension Benefits	Dec. 31, 2011 Pension Benefits	Dec. 31, 2010 Pension Benefits	Dec. 31, 2012 Pension Benefits Pinnacle West	Dec. 31, 2011 Pension Benefits Pinnacle West	Dec. 31, 2012 Pension Benefits Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Pension Benefits Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2012 Pension Benefits Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Pension Benefits Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2012 Pension Benefits Significant Unobservable Inputs (Level 3) Pinnacle West	Dec. 31, 2012 Pension Benefits Counterparty Netting and Other Pinnacle West	Dec. 31, 2011 Pension Benefits Counterparty Netting and Other Pinnacle West	Dec. 31, 2012 Pension Benefits Fixed income securities.	Dec. 31, 2012 Pension Benefits Return-generating assets	Dec. 31, 2012 Pension Benefits Cash and cash equivalent funds Pinnacle West	Dec. 31, 2011 Pension Benefits Cash and cash equivalent funds Pinnacle West	Dec. 31, 2012 Pension Benefits Cash and cash equivalent funds Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Pension Benefits Cash and cash equivalent funds Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2012 Pension Benefits Corporate debt Pinnacle West	Dec. 31, 2011 Pension Benefits Corporate debt Pinnacle West	Dec. 31, 2012 Pension Benefits Corporate debt Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Pension Benefits Corporate debt Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2012 Pension Benefits U.S. Treasury Pinnacle West	Dec. 31, 2011 Pension Benefits U.S. Treasury Pinnacle West	Dec. 31, 2012 Pension Benefits U.S. Treasury Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Pension Benefits U.S. Treasury Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2012 Pension Benefits Other Pinnacle West	Dec. 31, 2011 Pension Benefits Other Pinnacle West	Dec. 31, 2012 Pension Benefits Other Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Pension Benefits Other Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2012 Pension Benefits Developed equities	Dec. 31, 2012 Pension Benefits Emerging equities	Dec. 31, 2012 Pension Benefits Alternative investments	Dec. 31, 2012 Pension Benefits U.S. Companies, Equities Pinnacle West	Dec. 31, 2011 Pension Benefits U.S. Companies, Equities Pinnacle West	Dec. 31, 2012 Pension Benefits U.S. Companies, Equities Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Pension Benefits U.S. Companies, Equities Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2012 Pension Benefits International Companies, Equities Pinnacle West	Dec. 31, 2011 Pension Benefits International Companies, Equities Pinnacle West	Dec. 31, 2012 Pension Benefits International Companies, Equities Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Pension Benefits International Companies, Equities Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2012 Pension Benefits U.S. Equities Pinnacle West	Dec. 31, 2011 Pension Benefits U.S. Equities Pinnacle West	Dec. 31, 2012 Pension Benefits U.S. Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Pension Benefits U.S. Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2012 Pension Benefits International Equities Pinnacle West	Dec. 31, 2011 Pension Benefits International Equities Pinnacle West	Dec. 31, 2012 Pension Benefits International Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Pension Benefits International Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2012 Pension Benefits Real estate Pinnacle West	Dec. 31, 2011 Pension Benefits Real estate Pinnacle West	Dec. 31, 2012 Pension Benefits Real estate Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Pension Benefits Real estate Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2012 Pension Benefits Short-term investments and other Pinnacle West	Dec. 31, 2011 Pension Benefits Short-term investments and other Pinnacle West	Dec. 31, 2012 Pension Benefits Short-term investments and other Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Pension Benefits Short-term investments and other Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2012 Pension Benefits Short-term investments and other Significant Unobservable Inputs (Level 3)	Dec. 31, 2012 Pension Benefits Short-term investments and other Significant Unobservable Inputs (Level 3) Pinnacle West	Dec. 31, 2012 Pension Benefits Short-term investments and other Counterparty Netting and Other Pinnacle West	Dec. 31, 2011 Pension Benefits Short-term investments and other Counterparty Netting and Other Pinnacle West	Dec. 31, 2012 Other Benefits	Dec. 31, 2011 Other Benefits	Dec. 31, 2010 Other Benefits	Dec. 31, 2012 Other Benefits Maximum	Dec. 31, 2012 Other Benefits Pinnacle West	Dec. 31, 2011 Other Benefits Pinnacle West	Dec. 31, 2012 Other Benefits Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Other Benefits Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2012 Other Benefits Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Other Benefits Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2012 Other Benefits Counterparty Netting and Other Pinnacle West	Dec. 31, 2011 Other Benefits Counterparty Netting and Other Pinnacle West	Dec. 31, 2012 Other Benefits Fixed income securities. Minimum	Dec. 31, 2012 Other Benefits Cash and cash equivalent funds Pinnacle West	Dec. 31, 2011 Other Benefits Cash and cash equivalent funds Pinnacle West	Dec. 31, 2012 Other Benefits Cash and cash equivalent funds Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Other Benefits Cash and cash equivalent funds Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2012 Other Benefits Corporate debt Pinnacle West	Dec. 31, 2011 Other Benefits Corporate debt Pinnacle West	Dec. 31, 2012 Other Benefits Corporate debt Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Other Benefits Corporate debt Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2012 Other Benefits U.S. Treasury Pinnacle West	Dec. 31, 2011 Other Benefits U.S. Treasury Pinnacle West	Dec. 31, 2012 Other Benefits U.S. Treasury Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Other Benefits U.S. Treasury Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2012 Other Benefits Other Pinnacle West	Dec. 31, 2011 Other Benefits Other Pinnacle West	Dec. 31, 2012 Other Benefits Other Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Other Benefits Other Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2012 Other Benefits U.S. Companies, Equities Pinnacle West	Dec. 31, 2011 Other Benefits U.S. Companies, Equities Pinnacle West	Dec. 31, 2012 Other Benefits U.S. Companies, Equities Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Other Benefits U.S. Companies, Equities Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2012 Other Benefits International Companies, Equities Pinnacle West	Dec. 31, 2011 Other Benefits International Companies, Equities Pinnacle West	Dec. 31, 2012 Other Benefits International Companies, Equities Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Other Benefits International Companies, Equities Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2012 Other Benefits U.S. Equities Pinnacle West	Dec. 31, 2011 Other Benefits U.S. Equities Pinnacle West	Dec. 31, 2012 Other Benefits U.S. Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Other Benefits U.S. Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2012 Other Benefits International Equities Pinnacle West	Dec. 31, 2011 Other Benefits International Equities Pinnacle West	Dec. 31, 2012 Other Benefits International Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Other Benefits International Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2012 Other Benefits Real estate Pinnacle West	Dec. 31, 2011 Other Benefits Real estate Pinnacle West	Dec. 31, 2012 Other Benefits Real estate Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Other Benefits Real estate Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2012 Other Benefits Short-term investments and other Pinnacle West	Dec. 31, 2011 Other Benefits Short-term investments and other Pinnacle West	Dec. 31, 2012 Other Benefits Short-term investments and other Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Other Benefits Short-term investments and other Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2012 Other Benefits Short-term investments and other Counterparty Netting and Other Pinnacle West	Dec. 31, 2011 Other Benefits Short-term investments and other Counterparty Netting and Other Pinnacle West	Dec. 31, 2012 Other Benefits Short-term investments Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West
Retirement Plans and Other Benefits
Actual asset allocation (as a percent)													44.00%	56.00%																																																			55.00%									45.00%
Target asset allocation
Equities (as a percent)													50.00%	50.00%																	30.00%	6.00%	14.00%																																55.00%									25.00%
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets	$ 2,079,181	$ 1,850,550	$ 1,775,596	$ 2,079,181	$ 1,850,550	$ 807,879	$ 763,959	$ 1,268,946	$ 1,079,313	$ 2,419	$ (63)	$ 7,278			$ 579	$ 1,441	$ 579	$ 1,441	$ 607,749	$ 584,619	$ 607,749	$ 584,619	$ 232,161	$ 207,862	$ 232,161	$ 207,862	$ 67,992	$ 62,906	$ 67,992	$ 62,906				$ 531,291	$ 436,393	$ 531,291	$ 436,393	$ 43,848	$ 118,263	$ 43,848	$ 118,263	$ 176,694	$ 139,321	$ 176,694	$ 139,321	$ 271,735	$ 156,407	$ 271,735	$ 156,407	$ 117,854	$ 106,147	$ 117,854	$ 106,147	$ 29,278	$ 37,191	$ 26,922	$ 29,913	$ 2,419	$ 2,419	$ (63)	$ 7,278	$ 684,221	$ 608,663	$ 567,410		$ 684,221	$ 608,663	$ 333,146	$ 305,202	$ 350,029	$ 301,495	$ 1,046	$ 1,966		$ 60	$ 160	$ 60	$ 160	$ 163,306	$ 148,417	$ 163,306	$ 148,417	$ 112,558	$ 103,321	$ 112,558	$ 103,321	$ 33,998	$ 30,105	$ 33,998	$ 30,105	$ 205,714	$ 179,235	$ 205,714	$ 179,235	$ 14,412	$ 22,486	$ 14,412	$ 22,486	$ 60,038	$ 52,507	$ 60,038	$ 52,507	$ 76,969	$ 53,504	$ 76,969	$ 53,504	$ 9,378	$ 8,446	$ 9,378	$ 8,446	$ 7,788	$ 10,482	$ 6,340	$ 8,516	$ 1,046	$ 1,966	$ 402