Commitments, Contingencies And Uncertainties	3 Months Ended
Mar. 31, 2014
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 Financial Statements in the 2013 Form 10-K. In addition, see Note C above and Notes C and E of Notes to Financial Statements in the 2013 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 Financial Statements in the 2013 Form 10-K. In addition the 50 MW Macho Springs solar photovoltaic project located in Luna County, New Mexico, is projected to begin commercial operation before June 2014. Environmental Matters General. The Company is subject to extensive laws, regulations and permit requirements with respect to air and greenhouse gas emissions, water discharges, 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 Financial Statements in the 2013 Form 10-K. Clean Air Interstate Rule/Cross State Air Pollution Rule. The EPA promulgated the Cross-State Air Pollution Rule ("CSAPR") in August 2011, which rule 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. CSAPR was intended to replace the EPA's 2005 Clean Air Interstate Rule ("CAIR"). While the U.S. Court of Appeals for the District of Columbia Circuit ("D.C. Court of Appeals") vacated CSAPR in August 2012 and allowed CAIR to stand until the EPA issued a proper replacement, on April 29, 2014, the U.S. Supreme Court upheld CSAPR, remanding certain portions of CSAPR to the D.C. Court of Appeals for consideration. The Company will evaluate what impact, if any, the D.C. Court of Appeals subsequent holdings on remand will have on its operations. Other Laws and Regulations and Risks. The Company intends to cease its participation in Four Corners Generating Station ("Four Corners") at the expiration of the 50-year participation agreement in 2016. The Company believes that it has better economic and cleaner alternatives for serving the energy needs of its customers than coal-fired generation, which is subject to extensive regulation and litigation. For example, as a result of Arizona Public Service Company's ("APS") recent Best Available Retrofit Technology Federal Implementation Plan compliance strategy notification to the EPA, Four Corners is required to install expensive pollution control equipment in order to continue operation in the future. The Company's share of the cost of these controls is currently estimated by APS to be approximately $39 million if the Company were to extend its participation in the plant. In addition, the EPA has entered into a consent decree which would require it to issue its final rulemaking regarding the regulation of coal combustion residuals ("CCR") under the federal Resource, Conservation and Recovery Act by December 19, 2014. Once issued, the Company may be required to incur significant costs to address CCRs either generated in the past and disposed of at or from Four Corners, as well as CCRs generated in connection with the ongoing operations of Four Corners. Further, assured supplies of water are important for the Company's operations and assets, including Four Corners. Four Corners is located in a region that has been experiencing drought conditions which could affect the plant's water supply. Four Corners has accordingly been involved in negotiations and proceedings with third parties relating to water supply issues. The drought conditions and related negotiations and proceedings could adversely affect the amount of power available, or the price thereof, from Four Corners. The Company is negotiating with APS on the disposition of its ownership interest of Four Corners to allow the other participants to pursue a life extension of the Four Corners plant. 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 ("GHG") "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 GHG rulemaking addressing new power plants by September 20, 2013, and a rule for existing power plants by June 1, 2014. The formal proposal for new power plants was published in the Federal Register on January 8, 2014. The Company continues its review of the new proposal and plans to participate in the post-publication comment period (with extension) ending May 9, 2014. Given the very significant remaining uncertainties regarding these rules, 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. In particular, since July 2011, the U.S. Department of Justice (the "DOJ"), on behalf of the EPA, and 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. 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. The case is being held in abeyance while the parties seek to negotiate a settlement. On March 30, 2013, upon joint motion of the parties, the court issued an order deeming the motions to dismiss withdrawn without prejudice during pendency of the stay. At such time as the stay is lifted, APS, the Company and the other Four Corners participants may reinstate the motions to dismiss. On April 25, 2014, the stay was extended until May 15, 2014. 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. On December 19, 2013, the coal supplier and APS, on its own behalf and as operating agent for Four Corners, filed complaints 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.

Commitments, Contingencies and Uncertainties

For a full discussion of commitments and contingencies, see Note K of Notes to Financial Statements in the 2013 Form 10-K. In addition, see Note C above and Notes C and E of Notes to Financial Statements in the 2013 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 Financial Statements in the 2013 Form 10-K. In addition the 50 MW Macho Springs solar photovoltaic project located in Luna County, New Mexico, is projected to begin commercial operation before June 2014.

Environmental Matters

General. The Company is subject to extensive laws, regulations and permit requirements with respect to air and greenhouse gas emissions, water discharges, 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 Financial Statements in the 2013 Form 10-K.

Clean Air Interstate Rule/Cross State Air Pollution Rule. The EPA promulgated the Cross-State Air Pollution Rule ("CSAPR") in August 2011, which rule 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. CSAPR was intended to replace the EPA's 2005 Clean Air Interstate Rule ("CAIR"). While the U.S. Court of Appeals for the District of Columbia Circuit ("D.C. Court of Appeals") vacated CSAPR in August 2012 and allowed CAIR to stand until the EPA issued a proper replacement, on April 29, 2014, the U.S. Supreme Court upheld CSAPR, remanding certain portions of CSAPR to the D.C. Court of Appeals for consideration. The Company will evaluate what impact, if any, the D.C. Court of Appeals subsequent holdings on remand will have on its operations.

Other Laws and Regulations and Risks. The Company intends to cease its participation in Four Corners Generating Station ("Four Corners") at the expiration of the 50-year participation agreement in 2016. The Company believes that it has better economic and cleaner alternatives for serving the energy needs of its customers than coal-fired generation, which is subject to extensive regulation and litigation. For example, as a result of Arizona Public Service Company's ("APS") recent Best Available Retrofit Technology Federal Implementation Plan compliance strategy notification to the EPA, Four Corners is required to install expensive pollution control equipment in order to continue operation in the future. The Company's share of the cost of these controls is currently estimated by APS to be approximately $39 million if the Company were to extend its participation in the plant. In addition, the EPA has entered into a consent decree which would require it to issue its final rulemaking regarding the regulation of coal combustion residuals ("CCR") under the federal Resource, Conservation and Recovery Act by December 19, 2014. Once issued, the Company may be required to incur significant costs to address CCRs either generated in the past and disposed of at or from Four Corners, as well as CCRs generated in connection with the ongoing operations of Four Corners. Further, assured supplies of water are important for the Company's operations and assets, including Four Corners. Four Corners is located in a region that has been experiencing drought conditions which could affect the plant's water supply. Four Corners has accordingly been involved in negotiations and proceedings with third parties relating to water supply issues. The drought conditions and related negotiations and proceedings could adversely affect the amount of power available, or the price thereof, from Four Corners. The Company is negotiating with APS on the disposition of its ownership interest of Four Corners to allow the other participants to pursue a life extension of the Four Corners plant.

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 ("GHG") "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 GHG rulemaking addressing new power plants by September 20, 2013, and a rule for existing power plants by June 1, 2014. The formal proposal for new power plants was published in the Federal Register on January 8, 2014. The Company continues its review of the new proposal and plans to participate in the post-publication comment period (with extension) ending May 9, 2014. Given the very significant remaining uncertainties regarding these rules, 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. In particular, since July 2011, the U.S. Department of Justice (the "DOJ"), on behalf of the EPA, and 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.

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. The case is being held in abeyance while the parties seek to negotiate a settlement. On March 30, 2013, upon joint motion of the parties, the court issued an order deeming the motions to dismiss withdrawn without prejudice during pendency of the stay. At such time as the stay is lifted, APS, the Company and the other Four Corners participants may reinstate the motions to dismiss. On April 25, 2014, the stay was extended until May 15, 2014. 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. On December 19, 2013, the coal supplier and APS, on its own behalf and as operating agent for Four Corners, filed complaints 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.