Commitments, Contingencies And Uncertainties	9 Months Ended
Sep. 30, 2013
Commitments and Contingencies Disclosure [Abstract]
Commitments, Contingencies And Uncertainties	Commitments, Contingencies and Uncertainties For a full discussion of commitments and contingencies, see Note K of Notes to Consolidated Financial Statements in the 2012 Form 10-K. In addition, see Note C above and Notes C and E of Notes to Consolidated Financial Statements in the 2012 Form 10-K regarding matters related to wholesale power sales contracts and transmission contracts subject to regulation and Palo Verde, including decommissioning, spent nuclear fuel and waste disposal, and liability and insurance matters. Power Purchase and Sale Contracts To supplement its own generation and operating reserves, and to meet required renewable portfolio standards, the Company engages in firm power purchase arrangements which may vary in duration and amount based on evaluation of the Company’s resource needs, the economics of the transactions, and specific renewable portfolio requirements. For a full discussion of power purchase and sale contracts that the Company has entered into with various counterparties, see Note K of Notes to Consolidated Financial Statements in the 2012 Form 10-K. In addition to the contracts disclosed in the 2012 Form 10-K, in May 2013, the NMPRC approved the Company's agreement with Macho Springs Solar, LLC to purchase the entire generation output delivered from the 50 MW Macho Springs solar photovoltaic project located in Luna County, New Mexico. The term of the purchase is 20 years from the commercial operation date of the Macho Springs project which is projected to be May 1, 2014. In addition, on September 5, 2013, the Company entered into a purchased power agreement with Newman Solar LLC to purchase, for a term of 30 years, the total output from a solar photovoltaic generation facility of approximately 10 MW that Newman Solar LLC will construct, own and operate on land subleased from the Company in proximity to its Newman Generation Station. This solar project is expected to be online at the end of 2014. Environmental Matters General. The Company is subject to extensive laws, regulations and permit requirements with respect to air, soil and water quality, waste management and disposal, natural resources and other environmental matters by federal, state, regional, tribal and local authorities. Failure to comply with such laws, regulations and requirements can result in actions by authorities or other third parties that might seek to impose on the Company administrative, civil and/or criminal penalties or other sanctions. In addition, releases of pollutants or contaminants into the environment can result in costly cleanup liabilities. These laws, regulations and requirements are subject to change through modification or reinterpretation, or the introduction of new laws and regulations and, as a result, the Company may face additional capital and operating costs to comply. For a full discussion of certain key environmental issues, laws and regulations facing the Company see Note K of Notes to Consolidated Financial Statements in the 2012 Form 10-K. Clean Air Interstate Rule/Cross State Air Pollution Rule. The U.S. Environmental Protection Agency's ("EPA") Clean Air Interstate Rule ("CAIR"), as applied to the Company, involves requirements to limit emissions of nitrogen oxides ("NOx") and sulfur dioxide ("SO2") from certain of the Company's power plants in Texas and/or purchase allowances representing other parties' emissions reductions since 2009. While the U.S. Court of Appeals for the District of Columbia Circuit voided CAIR in 2008, on appeal the rule was reinstated until such time as the EPA promulgates a replacement rule. Because the appellate court in August of 2012 also vacated the EPA's proposed replacement, which is called the Cross-State Air Pollution Rule (“CSAPR”), CAIR remains in effect. On March 29, 2013, the U.S. Solicitor General petitioned the U.S. Supreme Court to review the D.C. Circuit's decision to vacate CSAPR, and on June 24, 2013, the Supreme Court agreed to hear the case. The timing and outcome of the Supreme Court decision is unknown, and in the meantime, the Company remains subject to CAIR. The annual reconciliation to comply with CAIR is due by March 31 of the following year. Climate Change. On June 25, 2013, President Obama set forth his plan to address climate change. He reiterated a goal of reducing greenhouse gas emissions "in the range of 17 percent" below 2005 levels by 2020. The plan included a variety of executive actions including future regulatory measures to reduce carbon emissions from power plants. In a White House memorandum of the same date, the President directed the EPA to issue a new proposal for greenhouse gas rulemaking addressing new power plants by September 20, 2013, and a rule for existing power plants by June 1, 2014. The EPA released a draft re-proposed carbon pollution rule for new power plants on September 20, 2013. The Company continues its review of the new proposal and plans to participate in the 60-day comment period after publication in the Federal Register. Given the very significant remaining uncertainties regarding when and how these rules will become effective, the Company believes it is impossible to meaningfully quantify the costs of these potential requirements at present. Environmental Litigation and Investigations. Since 2009, the EPA and certain environmental organizations have been scrutinizing, and in some cases, have filed lawsuits, relating to certain air emissions and air permitting matters related to Four Corners Generating Station ("Four Corners"). Since July 2011, the U.S. Department of Justice ("DOJ"), on behalf of the EPA, and Arizona Public Service Company ("APS") have been engaged in substantive settlement negotiations in an effort to resolve the pending matters. The allegations being addressed through settlement negotiations are that APS failed to obtain the necessary permits and install the controls necessary under the U.S. Clean Air Act ("CAA") to reduce SO2, NOx, and particular matter ("PM"), and that defendants failed to obtain an operating permit under Title V of the CAA that reflects applicable requirements imposed by law. In March 2012, the DOJ provided APS with a draft consent decree to settle the EPA matter, which decree contains specific provisions for the reduction and control of NOx, SO2, and PM, as well as provisions for a civil penalty, and expenditures on environmental mitigation projects with an emphasis on projects that address alleged harm to the Navajo Nation. Settlement discussions are on-going and the Company is unable to predict the outcome of these settlement negotiations. The Company has accrued a total of $0.5 million as a loss contingency related to this matter. Similar to other utilities in the western half of the U.S., the Company received notice that Earthjustice filed a lawsuit in the United States District Court for New Mexico on October 4, 2011 for alleged violations of the Prevention of Significant Deterioration ("PSD") provisions of the CAA related to Four Corners. On January 6, 2012, Earthjustice filed a First Amended Complaint adding claims for violations of the CAA's New Source Performance Standards ("NSPS") program. Among other things, the plaintiffs seek to have the court enjoin operations at Four Corners until APS applies for and obtains any required PSD permits and complies with the referenced NSPS program. The plaintiffs further request the court to order the payment of civil penalties, including a beneficial mitigation project. On April 2, 2012, APS and the other Four Corners' participants filed motions to dismiss with the court. Earthjustice filed their response briefs on May 16, 2012. APS filed reply briefs on June 22, 2012. Utility Air Regulatory Group filed an amicus brief, and plaintiffs were allowed until July 23, 2012 to respond to that amicus brief. In October 2013, a motion was filed to stay the case until December 1, 2013 in order to allow settlement discussions. The Company is unable to predict the outcome of this litigation. New Mexico Tax Matter Related to Coal Supplied to Four Corners On May 23, 2013, the New Mexico Taxation and Revenue Department issued a notice of assessment for coal severance surtax, penalty, and interest totaling approximately $30 million related to coal supplied under the coal supply agreement for Four Corners (the "Assessment"). The Company's share of the assessment is approximately $1.5 million. On behalf of the Four Corners participants, the coal supplier made a partial payment of the Assessment and immediately filed a refund claim with respect to that partial payment in August 2013. The New Mexico Taxation and Revenue Department denied the refund claim. Prior to year end, the coal supplier and APS, on its own behalf and as operating agent for Four Corners, intend to file a complaint with the New Mexico District Court contesting both the validity of the Assessment and the refund claim denial. APS believes the Assessment and the refund claim denial are without merit. The Company cannot predict the timing, results, or potential impacts of the outcome of this litigation. Union Matters The Company has approximately 1,000 employees, about 40% of whom are covered by a collective bargaining agreement. The International Brotherhood of Electrical Workers Local 960 (“Local 960”) represents the Company’s employees working primarily in the power plants, substations, line crews, meter reading and collection, facilities services, and customer service. The Company entered into a new collective bargaining agreement effective September 3, 2013, with Local 960 for a three-year term ending September 2, 2016. The agreement provides for pay increases of 3% on September 3, 2013, 3% on September 3, 2014 and 2.25% on September 3, 2015.

Commitments, Contingencies and Uncertainties

For a full discussion of commitments and contingencies, see Note K of Notes to Consolidated Financial Statements in the 2012 Form 10-K. In addition, see Note C above and Notes C and E of Notes to Consolidated Financial Statements in the 2012 Form 10-K regarding matters related to wholesale power sales contracts and transmission contracts subject to regulation and Palo Verde, including decommissioning, spent nuclear fuel and waste disposal, and liability and insurance matters.

Power Purchase and Sale Contracts

To supplement its own generation and operating reserves, and to meet required renewable portfolio standards, the Company engages in firm power purchase arrangements which may vary in duration and amount based on evaluation of the Company’s resource needs, the economics of the transactions, and specific renewable portfolio requirements. For a full discussion of power purchase and sale contracts that the Company has entered into with various counterparties, see Note K of Notes to Consolidated Financial Statements in the 2012 Form 10-K. In addition to the contracts disclosed in the 2012 Form 10-K, in May 2013, the NMPRC approved the Company's agreement with Macho Springs Solar, LLC to purchase the entire generation output delivered from the 50 MW Macho Springs solar photovoltaic project located in Luna County, New Mexico. The term of the purchase is 20 years from the commercial operation date of the Macho Springs project which is projected to be May 1, 2014. In addition, on September 5, 2013, the Company entered into a purchased power agreement with Newman Solar LLC to purchase, for a term of 30 years, the total output from a solar photovoltaic generation facility of approximately 10 MW that Newman Solar LLC will construct, own and operate on land subleased from the Company in proximity to its Newman Generation Station. This solar project is expected to be online at the end of 2014.

Environmental Matters

General. The Company is subject to extensive laws, regulations and permit requirements with respect to air, soil and water quality, waste management and disposal, natural resources and other environmental matters by federal, state, regional, tribal and local authorities. Failure to comply with such laws, regulations and requirements can result in actions by authorities or other third parties that might seek to impose on the Company administrative, civil and/or criminal penalties or other sanctions. In addition, releases of pollutants or contaminants into the environment can result in costly cleanup liabilities. These laws, regulations and requirements are subject to change through modification or reinterpretation, or the introduction of new laws and regulations and, as a result, the Company may face additional capital and operating costs to comply. For a full discussion of certain key environmental issues, laws and regulations facing the Company see Note K of Notes to Consolidated Financial Statements in the 2012 Form 10-K.

Clean Air Interstate Rule/Cross State Air Pollution Rule. The U.S. Environmental Protection Agency's ("EPA") Clean Air Interstate Rule ("CAIR"), as applied to the Company, involves requirements to limit emissions of nitrogen oxides ("NOx") and sulfur dioxide ("SO2") from certain of the Company's power plants in Texas and/or purchase allowances representing other parties' emissions reductions since 2009. While the U.S. Court of Appeals for the District of Columbia Circuit voided CAIR in 2008, on appeal the rule was reinstated until such time as the EPA promulgates a replacement rule. Because the appellate court in August of 2012 also vacated the EPA's proposed replacement, which is called the Cross-State Air Pollution Rule (“CSAPR”), CAIR remains in effect. On March 29, 2013, the U.S. Solicitor General petitioned the U.S. Supreme Court to review the D.C. Circuit's decision to vacate CSAPR, and on June 24, 2013, the Supreme Court agreed to hear the case. The timing and outcome of the Supreme Court decision is unknown, and in the meantime, the Company remains subject to CAIR. The annual reconciliation to comply with CAIR is due by March 31 of the following year.

Climate Change. On June 25, 2013, President Obama set forth his plan to address climate change. He reiterated a goal of reducing greenhouse gas emissions "in the range of 17 percent" below 2005 levels by 2020. The plan included a variety of executive actions including future regulatory measures to reduce carbon emissions from power plants. In a White House memorandum of the same date, the President directed the EPA to issue a new proposal for greenhouse gas rulemaking addressing new power plants by September 20, 2013, and a rule for existing power plants by June 1, 2014. The EPA released a draft re-proposed carbon pollution rule for new power plants on September 20, 2013. The Company continues its review of the new proposal and plans to participate in the 60-day comment period after publication in the Federal Register. Given the very significant remaining uncertainties regarding when and how these rules will become effective, the Company believes it is impossible to meaningfully quantify the costs of these potential requirements at present.

Environmental Litigation and Investigations. Since 2009, the EPA and certain environmental organizations have been scrutinizing, and in some cases, have filed lawsuits, relating to certain air emissions and air permitting matters related to Four Corners Generating Station ("Four Corners"). Since July 2011, the U.S. Department of Justice ("DOJ"), on behalf of the EPA, and Arizona Public Service Company ("APS") have been engaged in substantive settlement negotiations in an effort to resolve the pending matters. The allegations being addressed through settlement negotiations are that APS failed to obtain the necessary permits and install the controls necessary under the U.S. Clean Air Act ("CAA") to reduce SO2, NOx, and particular matter ("PM"), and that defendants failed to obtain an operating permit under Title V of the CAA that reflects applicable requirements imposed by law. In March 2012, the DOJ provided APS with a draft consent decree to settle the EPA matter, which decree contains specific provisions for the reduction and control of NOx, SO2, and PM, as well as provisions for a civil penalty, and expenditures on environmental mitigation projects with an emphasis on projects that address alleged harm to the Navajo Nation. Settlement discussions are on-going and the Company is unable to predict the outcome of these settlement negotiations. The Company has accrued a total of $0.5 million as a loss contingency related to this matter.

Similar to other utilities in the western half of the U.S., the Company received notice that Earthjustice filed a lawsuit in the United States District Court for New Mexico on October 4, 2011 for alleged violations of the Prevention of Significant Deterioration ("PSD") provisions of the CAA related to Four Corners. On January 6, 2012, Earthjustice filed a First Amended Complaint adding claims for violations of the CAA's New Source Performance Standards ("NSPS") program. Among other things, the plaintiffs seek to have the court enjoin operations at Four Corners until APS applies for and obtains any required PSD permits and complies with the referenced NSPS program. The plaintiffs further request the court to order the payment of civil penalties, including a beneficial mitigation project. On April 2, 2012, APS and the other Four Corners' participants filed motions to dismiss with the court. Earthjustice filed their response briefs on May 16, 2012. APS filed reply briefs on June 22, 2012. Utility Air Regulatory Group filed an amicus brief, and plaintiffs were allowed until July 23, 2012 to respond to that amicus brief. In October 2013, a motion was filed to stay the case until December 1, 2013 in order to allow settlement discussions. The Company is unable to predict the outcome of this litigation.

New Mexico Tax Matter Related to Coal Supplied to Four Corners

On May 23, 2013, the New Mexico Taxation and Revenue Department issued a notice of assessment for coal severance surtax, penalty, and interest totaling approximately $30 million related to coal supplied under the coal supply agreement for Four Corners (the "Assessment"). The Company's share of the assessment is approximately $1.5 million. On behalf of the Four Corners participants, the coal supplier made a partial payment of the Assessment and immediately filed a refund claim with respect to that partial payment in August 2013. The New Mexico Taxation and Revenue Department denied the refund claim. Prior to year end, the coal supplier and APS, on its own behalf and as operating agent for Four Corners, intend to file a complaint with the New Mexico District Court contesting both the validity of the Assessment and the refund claim denial. APS believes the Assessment and the refund claim denial are without merit. The Company cannot predict the timing, results, or potential impacts of the outcome of this litigation.

Union Matters

The Company has approximately 1,000 employees, about 40% of whom are covered by a collective bargaining agreement. The International Brotherhood of Electrical Workers Local 960 (“Local 960”) represents the Company’s employees working primarily in the power plants, substations, line crews, meter reading and collection, facilities services, and customer service. The Company entered into a new collective bargaining agreement effective September 3, 2013, with Local 960 for a three-year term ending September 2, 2016. The agreement provides for pay increases of 3% on September 3, 2013, 3% on September 3, 2014 and 2.25% on September 3, 2015.