Retirement Plans and Other Benefits (Details 3) (USD $) In Thousands, unless otherwise specified	12 Months Ended
	Dec. 31, 2011 U.S. Companies, Equities	Dec. 31, 2011 International Companies, Equities	Dec. 31, 2011 Other investments, Equities	Dec. 31, 2011 Pension Benefits	Dec. 31, 2010 Pension Benefits	Dec. 31, 2009 Pension Benefits	Dec. 31, 2011 Pension Benefits Pinnacle West	Dec. 31, 2010 Pension Benefits Pinnacle West	Dec. 31, 2011 Pension Benefits Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2010 Pension Benefits Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Pension Benefits Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2010 Pension Benefits Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Pension Benefits Counterparty Netting and Other Pinnacle West	Dec. 31, 2010 Pension Benefits Counterparty Netting and Other Pinnacle West	Dec. 31, 2011 Pension Benefits Fixed income securities.	Dec. 31, 2011 Pension Benefits Return-generating assets	Dec. 31, 2011 Pension Benefits Cash and cash equivalent funds Pinnacle West	Dec. 31, 2010 Pension Benefits Cash and cash equivalent funds 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, 2010 Pension Benefits Cash and cash equivalent funds Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Pension Benefits Corporate debt Pinnacle West	Dec. 31, 2010 Pension Benefits Corporate debt Pinnacle West	Dec. 31, 2011 Pension Benefits Corporate debt Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2010 Pension Benefits Corporate debt Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Pension Benefits U.S. Treasury Pinnacle West	Dec. 31, 2010 Pension Benefits U.S. Treasury Pinnacle West	Dec. 31, 2011 Pension Benefits U.S. Treasury Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2010 Pension Benefits U.S. Treasury Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Pension Benefits Other Pinnacle West	Dec. 31, 2010 Pension Benefits Other Pinnacle West	Dec. 31, 2011 Pension Benefits Other Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2010 Pension Benefits Other Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Pension Benefits U.S. Companies, Equities Pinnacle West	Dec. 31, 2010 Pension Benefits U.S. Companies, Equities 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, 2010 Pension Benefits U.S. Companies, Equities Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Pension Benefits International Companies, Equities Pinnacle West	Dec. 31, 2010 Pension Benefits International Companies, Equities Pinnacle West	Dec. 31, 2011 Pension Benefits International Companies, Equities Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2010 Pension Benefits International Companies, Equities Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2010 Pension Benefits Other investments, Equities Pinnacle West	Dec. 31, 2010 Pension Benefits Other investments, Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2010 Pension Benefits Other investments, Equities Counterparty Netting and Other Pinnacle West	Dec. 31, 2011 Pension Benefits U.S. Equities Pinnacle West	Dec. 31, 2010 Pension Benefits U.S. Equities Pinnacle West	Dec. 31, 2011 Pension Benefits U.S. Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2010 Pension Benefits U.S. Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Pension Benefits International Equities Pinnacle West	Dec. 31, 2010 Pension Benefits International Equities Pinnacle West	Dec. 31, 2011 Pension Benefits International Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2010 Pension Benefits International Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Pension Benefits Real estate Pinnacle West	Dec. 31, 2010 Pension Benefits Real estate Pinnacle West	Dec. 31, 2011 Pension Benefits Real estate Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2010 Pension Benefits Real estate Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2009 Pension Benefits Real estate Significant Unobservable Inputs (Level 3) Pinnacle West	Dec. 31, 2011 Pension Benefits Short-term investments and other Pinnacle West	Dec. 31, 2011 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 Counterparty Netting and Other Pinnacle West	Dec. 31, 2010 Pension Benefits Short-term investments Pinnacle West	Dec. 31, 2010 Pension Benefits Short-term investments Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Other Benefits	Dec. 31, 2010 Other Benefits	Dec. 31, 2009 Other Benefits	Dec. 31, 2011 Other Benefits Pinnacle West	Dec. 31, 2010 Other Benefits Pinnacle West	Dec. 31, 2011 Other Benefits Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2010 Other Benefits Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Other Benefits Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2010 Other Benefits Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Other Benefits Counterparty Netting and Other Pinnacle West	Dec. 31, 2010 Other Benefits Counterparty Netting and Other Pinnacle West	Dec. 31, 2011 Other Benefits Fixed income securities.	Dec. 31, 2011 Other Benefits Return-generating assets	Dec. 31, 2011 Other Benefits Cash and cash equivalent funds Pinnacle West	Dec. 31, 2010 Other Benefits Cash and cash equivalent funds 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, 2010 Other Benefits Cash and cash equivalent funds Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Other Benefits Corporate debt Pinnacle West	Dec. 31, 2010 Other Benefits Corporate debt Pinnacle West	Dec. 31, 2011 Other Benefits Corporate debt Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2010 Other Benefits Corporate debt Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Other Benefits U.S. Treasury Pinnacle West	Dec. 31, 2010 Other Benefits U.S. Treasury Pinnacle West	Dec. 31, 2011 Other Benefits U.S. Treasury Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2010 Other Benefits U.S. Treasury Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Other Benefits Other Pinnacle West	Dec. 31, 2010 Other Benefits Other Pinnacle West	Dec. 31, 2011 Other Benefits Other Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2010 Other Benefits Other Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Other Benefits U.S. Companies, Equities Pinnacle West	Dec. 31, 2010 Other Benefits U.S. Companies, Equities 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, 2010 Other Benefits U.S. Companies, Equities Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2011 Other Benefits International Companies, Equities Pinnacle West	Dec. 31, 2010 Other Benefits International Companies, Equities Pinnacle West	Dec. 31, 2011 Other Benefits International Companies, Equities Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2010 Other Benefits International Companies, Equities Quoted Prices in Active Markets for Identical Assets (Level 1) Pinnacle West	Dec. 31, 2010 Other Benefits Other investments, Equities Pinnacle West	Dec. 31, 2010 Other Benefits Other investments, Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2010 Other Benefits Other investments, Equities Counterparty Netting and Other Pinnacle West	Dec. 31, 2011 Other Benefits U.S. Equities Pinnacle West	Dec. 31, 2010 Other Benefits U.S. Equities Pinnacle West	Dec. 31, 2011 Other Benefits U.S. Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2010 Other Benefits U.S. Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Other Benefits International Equities Pinnacle West	Dec. 31, 2010 Other Benefits International Equities Pinnacle West	Dec. 31, 2011 Other Benefits International Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2010 Other Benefits International Equities Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2011 Other Benefits Real estate Pinnacle West	Dec. 31, 2010 Other Benefits Real estate Pinnacle West	Dec. 31, 2011 Other Benefits Real estate Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2010 Other Benefits Real estate Significant Other Observable Inputs (Level 2) Pinnacle West	Dec. 31, 2009 Other Benefits Real estate Significant Unobservable Inputs (Level 3) Pinnacle West	Dec. 31, 2011 Other Benefits Short-term investments and other Pinnacle West	Dec. 31, 2011 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 Counterparty Netting and Other Pinnacle West	Dec. 31, 2010 Other Benefits Short-term investments Pinnacle West	Dec. 31, 2010 Other Benefits Short-term investments Significant Other Observable Inputs (Level 2) Pinnacle West
Retirement Plans and Other Benefits
Actual asset allocation (as a percent)															46.00%	54.00%																																																									46.00%	54.00%
Target asset allocation
Equities (as a percent)	64.00%	27.00%
Alternative investments (as a percent)			9.00%
Fair value of Pinnacle West's pension plan and other postretirement benefit plan assets, by asset category
Fair value of plan assets				$ 1,850,550	$ 1,775,596	$ 1,461,808	$ 1,850,550	$ 1,775,596	$ 763,959	$ 757,755	$ 1,079,313	$ 1,009,770	$ 7,278	$ 8,071			$ 1,441	$ 2,375	$ 1,441	$ 2,375	$ 584,619	$ 508,946	$ 584,619	$ 508,946	$ 207,862	$ 163,313	$ 207,862	$ 163,313	$ 62,906	$ 53,358	$ 62,906	$ 53,358	$ 436,393	$ 462,973	$ 436,393	$ 462,973	$ 118,263	$ 129,094	$ 118,263	$ 129,094	$ 13,620	$ 5,549	$ 8,071	$ 139,321	$ 146,705	$ 139,321	$ 146,705	$ 156,407	$ 177,114	$ 156,407	$ 177,114	$ 106,147	$ 92,454	$ 106,147	$ 92,454	$ 64,212	$ 37,191	$ 29,913	$ 7,278	$ 25,644	$ 25,644	$ 608,663	$ 567,410	$ 490,455	$ 608,663	$ 567,410	$ 305,202	$ 279,068	$ 301,495	$ 286,308	$ 1,966	$ 2,034			$ 160	$ 243	$ 160	$ 243	$ 148,417	$ 118,660	$ 148,417	$ 118,660	$ 103,321	$ 74,049	$ 103,321	$ 74,049	$ 30,105	$ 24,456	$ 30,105	$ 24,456	$ 179,235	$ 179,655	$ 179,235	$ 179,655	$ 22,486	$ 25,121	$ 22,486	$ 25,121	$ 2,399	$ 365	$ 2,034	$ 52,507	$ 54,144	$ 52,507	$ 54,144	$ 53,504	$ 61,455	$ 53,504	$ 61,455	$ 8,446	$ 7,357	$ 8,446	$ 7,357	$ 6,504	$ 10,482	$ 8,516	$ 1,966	$ 19,871	$ 19,871