Regulation	3 Months Ended
Mar. 31, 2016
Public Utilities, General Disclosures [Abstract]
Regulation	Regulation General The rates and services of the Company are regulated by incorporated municipalities in Texas, the Public Utility Commission of Texas ("PUCT"), the New Mexico Public Regulation Commission ("NMPRC"), and the Federal Regulatory Commission ("FERC"). Municipal orders, ordinances and other agreements regarding rates and services adopted by Texas municipalities are subject to review and approval by the PUCT. The FERC has jurisdiction over the Company's wholesale (sales for resale) transactions, transmission service and compliance with federally-mandated reliability standards. The decisions of the PUCT, the NMPRC and the FERC are subject to judicial review. Texas Regulatory Matters 2012 Texas Retail Rate Case. On April 17, 2012, the El Paso City Council approved the settlement of the Company's 2012 Texas retail rate case and fuel reconciliation in PUCT Docket No. 40094. The PUCT issued a final order approving the settlement on May 23, 2012 and the rates were effective as of May 1, 2012. As part of the 2012 Texas retail rate settlement, the Company agreed to submit a future fuel reconciliation request covering the period beginning July 1, 2009 and ending no later than June 30, 2013 by December 31, 2013 or as part of its next rate case, if earlier. The Company filed a fuel reconciliation request covering the period July 1, 2009 through March 31, 2013, as discussed below. The 2012 Texas retail rate settlement also provided for the continuation of the energy efficiency cost recovery factor and the military base discount recovery factor. Both of these surcharges require annual filings to reconcile and revise the recovery factors. 2015 Texas Retail Rate Case Filing. On August 10, 2015, the Company filed with the City of El Paso, other municipalities incorporated in its Texas service territory, and the PUCT in Docket No. 44941, a request for an annual increase in non-fuel base revenues of approximately $71.5 million. The request includes recovery of new plant placed into service since 2009. Rate case expenses of $1.8 million, amortized over 3 years, were included in the $71.5 million request. On January 15, 2016, the Company filed its rebuttal testimony modifying the requested increase to $63.3 million, which included severing the $1.8 million of rate case expenses from this rate case. A motion was granted to sever and establish a new docket (Docket No. 45475). The Company has invoked its statutory right to have its new rates relate back for consumption on and after January 12, 2016, which is the 155th day after the filing. The difference in rates that would have been billed will be surcharged or refunded to customers beginning after the PUCT's final order in Docket No. 44941. The PUCT has the authority to require the Company to surcharge or refund such difference over a period not to exceed 18 months. On January 21, 2016, the Company, the City of El Paso, the PUCT Staff, the Office of Public Utility Counsel and Texas Industrial Energy Consumers filed a joint motion to abate the procedural schedule to facilitate settlement talks. This motion was granted. On March 29, 2016, the majority of parties to PUCT Docket No. 44941 filed a non-unanimous Stipulation and Agreement ("Settlement Agreement"), together with a motion to implement it. The Settlement Agreement would resolve all issues in this rate case except for one revenue requirement issue involving the Company's interest in Units 4 and 5 of the Four Corners power plant ("Four Corners"). The Settlement Agreement includes, among other things: (i) an annual non-fuel base rate increase of $37 million; (ii) the potential for an additional base rate increase of $8 million related to Four Corners costs after a hearing and decision; (iii) a change in estimated asset lives which would lower annual depreciation expense by approximately $8.5 million; (iv) a return on equity of 9.7% for AFUDC purposes; and (v) a determination that substantially all new plant in service was reasonable and necessary and therefore would be recoverable in rate base. Approximately 76% of the Company's customers are in Texas. The Administrative Law Judges ("ALJs") hearing the case approved interim rates for the $37 million annual increase outlined in the Settlement Agreement on March 30, 2016. The interim rates are effective as of April 1, 2016 and are subject to refund or surcharge pending resolution by the PUCT. Four parties have indicated that they oppose the Settlement Agreement, and they are entitled to a hearing on the Settlement Agreement. On April 22, 2016, the ALJs issued an Order Setting a Procedural Schedule, which among other things, calls for a hearing on June 21-22, 2016 on the merits of the proposed settlement of the rate case, not including the Four Corners issue. The Company cannot predict the timing and outcome of this rate case at this time. Given the uncertainty regarding the ultimate resolution of this rate case, the Company did not record any impacts of the Settlement Agreement in the first quarter of 2016. As discussed above, upon resolution of this rate case, the Company expects to record revenues under the new rate structure for consumption on or after January 12, 2016. Energy Efficiency Cost Recovery Factor. The Company made its annual filing to establish its energy efficiency cost recovery factor for 2015 on May 1, 2014. In addition to projected energy efficiency costs for 2015 and true-up to prior year actual costs, the Company requested approval of a $2.0 million bonus for the 2013 energy efficiency program results in accordance with PUCT rules. The PUCT approved the Company's request at its November 14, 2014 open meeting. The Company recorded the $2.0 million bonus as operating revenue in the fourth quarter of 2014. On May 1, 2015, the Company made its annual filing to establish its energy efficiency cost recovery factor for 2016. In addition to projected energy efficiency costs for 2016 and a true-up to prior year actual costs, the Company requested approval of a $1.0 million bonus for the 2014 energy efficiency program results in accordance with PUCT rules. This case was assigned PUCT Docket No. 44677. A stipulation and settlement agreement was filed September 24, 2015 and the PUCT approved the settlement on November 5, 2015. The settlement approved by the PUCT includes a performance bonus of $1.0 million. The Company recorded the performance bonus as operating revenue in the fourth quarter of 2015. On April 29, 2016, the Company made its annual filing to establish its energy efficiency cost recovery factor for 2017. In addition to projected energy efficiency costs for 2017 and true-up to prior year actual costs, the Company requested approval of a $668 thousand bonus for the 2015 energy efficiency program results in accordance with PUCT rules. This case was assigned PUCT Docket No. 45855. The Company expects the Commission will make a final decision in the proceeding before the end of 2016. Fuel and Purchased Power Costs. The Company's actual fuel costs, including purchased power energy costs, are recovered from customers through a fixed fuel factor. The PUCT has adopted a fuel cost recovery rule (the "Texas Fuel Rule") that allows the Company to seek periodic adjustments to its fixed fuel factor. The Company can seek to revise its fixed fuel factor based upon the approved formula at least four months after its last revision except in the month of December. The Texas Fuel Rule requires the Company to request to refund fuel costs in any month when the over-recovery balance exceeds a threshold material amount and it expects fuel costs to continue to be materially over-recovered. The Texas Fuel Rule also permits the Company to seek to surcharge fuel under-recoveries in any month the balance exceeds a threshold material amount and it expects fuel cost recovery to continue to be materially under-recovered. Fuel over- and under-recoveries are considered material when they exceed 4% of the previous twelve months' fuel costs. All such fuel revenue and expense activities are subject to periodic final review by the PUCT in fuel reconciliation proceedings. On April 15, 2015, the Company filed a request, which was assigned PUCT Docket No. 44633, to reduce its fixed fuel factor by approximately 24% to reflect reduced fuel expenses primarily related to a reduction in the price of natural gas used to generate power. The over-recovered balance was below the PUCT's materiality threshold. The reduction in the fixed fuel factor was effective on an interim basis May 1, 2015 and approved by the PUCT on May 20, 2015. As of March 31, 2016, the Company had over-recovered fuel costs in the amount of $5.2 million for the Texas jurisdiction. Fuel Reconciliation Proceeding. Pursuant to the 2012 Texas retail rate settlement discussed above, on September 27, 2013, the Company filed an application with the PUCT, designated as PUCT Docket No. 41852, to reconcile $545.3 million of fuel and purchased power expenses incurred during the 45-month period from July 1, 2009 through March 31, 2013. A settlement was reached and a final order was issued by the PUCT on July 11, 2014 with no significant adjustments. The PUCT's final order completes the regulatory review and reconciliation of the Company's fuel expenses for the period through March 31, 2013. The Company is required to file an application by the end of the third quarter of 2016 for fuel reconciliation of the Company's fuel expenses for the period through March 31, 2016. Montana Power Station ("MPS") Approvals. The Company has received a Certificate of Convenience and Necessity ("CCN") from the PUCT to construct four natural gas fired generating units at MPS in El Paso County, Texas. The Company also obtained air permits from the Texas Commission on Environmental Quality (the "TCEQ") and the U.S. Environmental Protection Agency (the "EPA"). MPS Units 1 and 2 and associated transmission lines and common facilities were completed and placed into service in March 2015. MPS Unit 3 was completed and placed into service on May 3, 2016. Community Solar. On June 8, 2015, the Company filed a petition with the PUCT to initiate a community solar program to include construction and ownership of a 3 MW solar photovoltaic system located at MPS. Participation will be on a voluntary basis, and customers will contract for a set capacity (kW) amount and receive all energy produced. This case was assigned PUCT Docket No. 44800. The Company has presented settlement documents to the other parties and the other parties are in the process of evaluating them. Four Corners Generating Station ("Four Corners"). On February 17, 2015, the Company and Arizona Public Service Company ("APS") entered into an asset purchase agreement (the "Purchase and Sale Agreement") providing for the purchase by APS of the Company's interests in Four Corners. The Purchase and Sale Agreement included a projected cash purchase price which will be equal to the net book value of our interest in Four Corners at the date of close. The net book value at June 30, 2016 is expected to approximate $29 million. The Company will also be reimbursed for certain undepreciated capital expenditures, that are projected to approximate $5 million at June 30, 2016. The purchase price will be adjusted downward to reflect APS's assumption of the Company's obligation to pay for future plant decommissioning and mine reclamation expenses estimated at July 6, 2016 to be $7.0 million and $19.3 million, respectively. On June 10, 2015, the Company filed an application in Texas requesting reasonableness and public interest findings and certain rate and accounting findings related to the Purchase and Sale Agreement. The anticipated closing date of the sale is July 6, 2016, pending regulatory approval. This case was assigned PUCT Docket No. 44805. On January 11, 2016, the PUCT referred the case to the State Office of Administrative Hearings ("SOAH") for an administrative hearing. On February 5, 2016, an administrative law judge ("ALJ") of the SOAH issued an order adopting a procedural schedule. The procedural schedule calls for a hearing on the merits to be held on October 6-7, 2016. At March 31, 2016, the regulatory asset associated with mine reclamation costs for our Texas jurisdiction approximated $7.4 million. At the PUCT's February 11, 2016 open meeting, Commissioners discussed whether the Company's requests in this docket should instead be addressed in a rate case. On February 11, 2016, the PUCT issued its Order Requesting Briefing on Threshold Legal/Policy Issues, seeking briefs from the parties on the issue "Should the Commission dismiss this docket?" Such briefs were filed January 25, 2016. In a March 23, 2016 order, the PUCT determined not to dismiss the reasonableness and public interest issues in this docket but to consider the requested rate and accounting findings, including mine reclamation costs, in the Company's next rate case, which is expected to be filed in early 2017. The Company currently continues to recover its mine reclamation costs in Texas under previous orders and decisions of the PUCT. If any future determinations made by our regulators result in changes to how existing regulatory assets or previously incurred costs for Four Corners are recovered in rates, any such changes would be recognized only when it becomes probable future cash flows will change as a result of such regulatory actions. Other Required Approvals. The Company has obtained other required approvals for tariffs and approvals as required by the Public Utility Regulatory Act (the "PURA") and the PUCT. New Mexico Regulatory Matters 2009 New Mexico Stipulation. On December 10, 2009, the NMPRC issued a final order conditionally approving the stipulated rates in NMPRC Case No. 09-00171-UT. The stipulated rates went into effect with January 2010 bills. The stipulated rates provide for an Efficient Use of Energy Factor Rate Rider to recover energy efficiency expenditures which are updated annually for adjustment to the recovery factors. 2015 New Mexico Rate Case Filing. On May 11, 2015, the Company filed with the NMPRC in Case No. 15-00127-UT, for an annual increase in non-fuel base rates of approximately $8.6 million or 7.1%. The request includes recovery of new plant placed into service since the last time rates were adjusted in 2009. The filing also requests an annual reduction of $15.4 million, or 21.5%, for fuel and purchased power costs recovered in base rates. The reduction in fuel and purchased power rates reflects reduced fuel prices and improvements in system heat rates due to new generating unit additions. Subsequently, the Company reduced its requested increase in non-fuel base rates to approximately $6.4 million. On February 16, 2016, the Hearing Examiner issued a Recommended Decision to the NMPRC proposing an annual increase in non-fuel base rates of approximately $640 thousand. The Company filed exceptions to the Recommended Decision to be considered by the NMPRC. During the open meeting on May 4, 2016, the NMPRC again extended the suspension period until June 10, 2016, by which time the NMPRC is expected to issue a final order. Approximately 24% of the Company's customers are in New Mexico. The Company cannot predict the outcome of the rate case at this time. Fuel and Purchased Power Costs. Fuel and purchased power costs are recovered through base rates and a Fuel and Purchased Power Cost Adjustment Clause (the "FPPCAC") that accounts for changes in the costs of fuel relative to the amount included in base rates. On January 8, 2014, the NMPRC approved the continuation of the FPPCAC without modification in NMPRC Case No. 13-00380-UT. Fuel and purchased power costs are reconciled to actual costs on a monthly basis and recovered or refunded to customers the second succeeding month. The Company recovers costs related to Palo Verde Unit 3 capacity and energy in New Mexico through the FPPCAC as purchased power using a proxy market price approved in the 2014 FPPCAC continuation. At March 31, 2016, the Company had a net fuel over-recovery balance of $2.8 million in New Mexico. Montana Power Station Approvals. The Company has received a CCN from the NMPRC to construct four units at MPS and the associated transmission lines. The Company also obtained all necessary air permits from the TCEQ and the EPA. A final order in NMPRC Case No. 13-00297-UT approving the CCN for MPS Units 3 and 4 was issued on June 11, 2014. MPS Units 1 and 2 and MPS to Caliente and MPS In & Out transmission lines were completed and placed into service in March 2015. MPS Unit 3 was completed and placed into service on May 3, 2016. Four Corners. On February 17, 2015, the Company and APS entered into the Purchase and Sale Agreement providing for the purchase by APS of the Company's interests in Four Corners. On April 27, 2015, the Company filed an application requesting all necessary regulatory approvals to sell its ownership interest in Four Corners. The anticipated closing date of the sale is July 6, 2016, pending regulatory approval. This case was assigned NMPRC Case No. 15-00109-UT. On February 2, 2016, the Company filed a joint stipulation with the NMPRC reflecting a settlement agreement among the Commission Utility Division Staff, the Company and the New Mexico Attorney General proposing approval of abandonment and sale of its seven percent minority ownership interest in Four Corners Units 4 and 5 and common facilities to APS. An addendum to the joint stipulation was subsequently filed and the joint stipulation is unopposed. A hearing in the case was held on February 16, 2016, and the Hearing Examiner issued a Certification of Stipulation on April 22, 2016 recommending approval of the joint stipulation without modification. A NMPRC final order is expected in the first half of 2016. Based on the joint stipulation and addendum, no significant gain or loss is expected to be realized upon closing of the sale. 5 MW Holloman Air Force Base ("HAFB") Facility CCN. On June 15, 2015, the Company filed a petition with the NMPRC requesting CCN authorization to construct a 5 MW solar-powered generation facility to be located at HAFB in the Company's service territory in New Mexico. The new facility will be a dedicated Company-owned resource serving HAFB. This case was assigned NMPRC Case No. 15-00185-UT. On October 7, 2015, the NMPRC issued a Final Order accepting the Hearing Examiner’s Recommended Decision to approve the CCN, as modified. The Company and HAFB are in discussions for a power sales agreement for the facility to replace the existing load retention agreement. Issuance of Long-Term Debt and Guarantee of Debt. On October 7, 2015, the Company received approval in NMPRC Case No. 15-00280-UT to issue up to $310 million in new long-term debt; and to guarantee the issuance of up to $65 million of new debt by Rio Grande Resources Trust ("RGRT") to finance future purchases of nuclear fuel and to refinance existing nuclear fuel debt obligations. This approval supersedes prior approvals. Under this authorization, on March 24, 2016, the Company issued $150 million in aggregate principal amount of 5.00% Senior Notes due December 1, 2044. The net proceeds from the issuance of these senior notes, after deducting the underwriters' commission, were $158.1 million. These proceeds include accrued interest of $2.4 million and a $7.1 million premium before expenses. These senior notes constitute an additional issuance of the Company's 5.00% Senior Notes due 2044, of which $150 million was previously issued on December 1, 2014, for a total principal amount outstanding of $300 million. Other Required Approvals. The Company has obtained other required approvals for other tariffs, securities transactions, recovery of energy efficiency costs through a base rate rider and other approvals as required by the NMPRC. Federal Regulatory Matters Four Corners. On June 26, 2015, APS filed an application requesting authorization from FERC to purchase 100% of the Company’s ownership interest in Units 4 and 5 of Four Corners and the associated transmission interconnection facilities and rights. On December 22, 2015, FERC issued an order approving the proposed transaction. Public Service Company of New Mexico ("PNM") Transmission Rate Case. On December 31, 2012, PNM filed with FERC to change its method of transmission rate recovery for its transmission delivery services from stated rates to formula rates. The Company takes transmission service from PNM and is among the PNM transmission customers affected by PNM's shift to formula rates. On March 1, 2013, the FERC issued an order rejecting in part PNM's filing, and establishing settlement judge and hearing procedures. On March 20, 2015, PNM filed with FERC a settlement agreement and offer of settlement resolving all issues set for hearing in the proceeding. On March 25, 2015, the Chief Judge issued an order granting PNM's motion to implement the settled rates. On March 17, 2016, FERC issued an order approving the settlement. Revolving Credit Facility; Issuance of Long-Term Debt and Guarantee of Debt. On October 19, 2015, the FERC issued an order in Docket No. ES15-66-000 approving the Company’s filing to issue short-term debt under its existing revolving credit facility ("RCF") up to $400 million outstanding at any time, to issue up to $310 million in long-term debt, and to guarantee the issuance of up to $65 million of new long-term debt by RGRT to finance future nuclear fuel purchases. The authorization is effective from November 15, 2015 through November 15, 2017. This approval supersedes prior approvals. Under this authorization, on March 24, 2016, the Company issued $150 million in aggregate principal amount of 5.00% Senior Notes due December 1, 2044. The net proceeds from the issuance of these senior notes, after deducting the underwriters' commission, were $158.1 million. These proceeds include accrued interest of $2.4 million and a $7.1 million premium before expenses. These senior notes constitute an additional issuance of the Company's 5.00% Senior Notes due 2044, of which $150 million was previously issued on December 1, 2014, for a total principal amount outstanding of $300 million. Other Required Approvals. The Company has obtained required approvals for rates and tariffs, securities transactions and other approvals as required by the FERC.

Regulation

General

The rates and services of the Company are regulated by incorporated municipalities in Texas, the Public Utility Commission of Texas ("PUCT"), the New Mexico Public Regulation Commission ("NMPRC"), and the Federal Regulatory Commission ("FERC"). Municipal orders, ordinances and other agreements regarding rates and services adopted by Texas municipalities are subject to review and approval by the PUCT. The FERC has jurisdiction over the Company's wholesale (sales for resale) transactions, transmission service and compliance with federally-mandated reliability standards. The decisions of the PUCT, the NMPRC and the FERC are subject to judicial review.

Texas Regulatory Matters

2012 Texas Retail Rate Case. On April 17, 2012, the El Paso City Council approved the settlement of the Company's 2012 Texas retail rate case and fuel reconciliation in PUCT Docket No. 40094. The PUCT issued a final order approving the settlement on May 23, 2012 and the rates were effective as of May 1, 2012. As part of the 2012 Texas retail rate settlement, the Company agreed to submit a future fuel reconciliation request covering the period beginning July 1, 2009 and ending no later than June 30, 2013 by December 31, 2013 or as part of its next rate case, if earlier. The Company filed a fuel reconciliation request covering the period July 1, 2009 through March 31, 2013, as discussed below. The 2012 Texas retail rate settlement also provided for the continuation of the energy efficiency cost recovery factor and the military base discount recovery factor. Both of these surcharges require annual filings to reconcile and revise the recovery factors.

2015 Texas Retail Rate Case Filing. On August 10, 2015, the Company filed with the City of El Paso, other municipalities incorporated in its Texas service territory, and the PUCT in Docket No. 44941, a request for an annual increase in non-fuel base revenues of approximately $71.5 million. The request includes recovery of new plant placed into service since 2009. Rate case expenses of $1.8 million, amortized over 3 years, were included in the $71.5 million request. On January 15, 2016, the Company filed its rebuttal testimony modifying the requested increase to $63.3 million, which included severing the $1.8 million of rate case expenses from this rate case. A motion was granted to sever and establish a new docket (Docket No. 45475). The Company has invoked its statutory right to have its new rates relate back for consumption on and after January 12, 2016, which is the 155th day after the filing. The difference in rates that would have been billed will be surcharged or refunded to customers beginning after the PUCT's final order in Docket No. 44941. The PUCT has the authority to require the Company to surcharge or refund such difference over a period not to exceed 18 months. On January 21, 2016, the Company, the City of El Paso, the PUCT Staff, the Office of Public Utility Counsel and Texas Industrial Energy Consumers filed a joint motion to abate the procedural schedule to facilitate settlement talks. This motion was granted.

On March 29, 2016, the majority of parties to PUCT Docket No. 44941 filed a non-unanimous Stipulation and Agreement ("Settlement Agreement"), together with a motion to implement it. The Settlement Agreement would resolve all issues in this rate case except for one revenue requirement issue involving the Company's interest in Units 4 and 5 of the Four Corners power plant ("Four Corners"). The Settlement Agreement includes, among other things: (i) an annual non-fuel base rate increase of $37 million; (ii) the potential for an additional base rate increase of $8 million related to Four Corners costs after a hearing and decision; (iii) a change in estimated asset lives which would lower annual depreciation expense by approximately $8.5 million; (iv) a return on equity of 9.7% for AFUDC purposes; and (v) a determination that substantially all new plant in service was reasonable and necessary and therefore would be recoverable in rate base. Approximately 76% of the Company's customers are in Texas.

The Administrative Law Judges ("ALJs") hearing the case approved interim rates for the $37 million annual increase outlined in the Settlement Agreement on March 30, 2016. The interim rates are effective as of April 1, 2016 and are subject to refund or surcharge pending resolution by the PUCT. Four parties have indicated that they oppose the Settlement Agreement, and they are entitled to a hearing on the Settlement Agreement. On April 22, 2016, the ALJs issued an Order Setting a Procedural Schedule, which among other things, calls for a hearing on June 21-22, 2016 on the merits of the proposed settlement of the rate case, not including the Four Corners issue. The Company cannot predict the timing and outcome of this rate case at this time.

Given the uncertainty regarding the ultimate resolution of this rate case, the Company did not record any impacts of the Settlement Agreement in the first quarter of 2016. As discussed above, upon resolution of this rate case, the Company expects to record revenues under the new rate structure for consumption on or after January 12, 2016.

Energy Efficiency Cost Recovery Factor. The Company made its annual filing to establish its energy efficiency cost recovery factor for 2015 on May 1, 2014. In addition to projected energy efficiency costs for 2015 and true-up to prior year actual costs, the Company requested approval of a $2.0 million bonus for the 2013 energy efficiency program results in accordance with PUCT rules. The PUCT approved the Company's request at its November 14, 2014 open meeting. The Company recorded the $2.0 million bonus as operating revenue in the fourth quarter of 2014.

On May 1, 2015, the Company made its annual filing to establish its energy efficiency cost recovery factor for 2016. In addition to projected energy efficiency costs for 2016 and a true-up to prior year actual costs, the Company requested approval of a $1.0 million bonus for the 2014 energy efficiency program results in accordance with PUCT rules. This case was assigned PUCT Docket No. 44677. A stipulation and settlement agreement was filed September 24, 2015 and the PUCT approved the settlement on November 5, 2015. The settlement approved by the PUCT includes a performance bonus of $1.0 million. The Company recorded the performance bonus as operating revenue in the fourth quarter of 2015.

On April 29, 2016, the Company made its annual filing to establish its energy efficiency cost recovery factor for 2017. In addition to projected energy efficiency costs for 2017 and true-up to prior year actual costs, the Company requested approval of a $668 thousand bonus for the 2015 energy efficiency program results in accordance with PUCT rules. This case was assigned PUCT Docket No. 45855. The Company expects the Commission will make a final decision in the proceeding before the end of 2016.

Fuel and Purchased Power Costs. The Company's actual fuel costs, including purchased power energy costs, are recovered from customers through a fixed fuel factor. The PUCT has adopted a fuel cost recovery rule (the "Texas Fuel Rule") that allows the Company to seek periodic adjustments to its fixed fuel factor. The Company can seek to revise its fixed fuel factor based upon the approved formula at least four months after its last revision except in the month of December. The Texas Fuel Rule requires the Company to request to refund fuel costs in any month when the over-recovery balance exceeds a threshold material amount and it expects fuel costs to continue to be materially over-recovered. The Texas Fuel Rule also permits the Company to seek to surcharge fuel under-recoveries in any month the balance exceeds a threshold material amount and it expects fuel cost recovery to continue to be materially under-recovered. Fuel over- and under-recoveries are considered material when they exceed 4% of the previous twelve months' fuel costs. All such fuel revenue and expense activities are subject to periodic final review by the PUCT in fuel reconciliation proceedings.

On April 15, 2015, the Company filed a request, which was assigned PUCT Docket No. 44633, to reduce its fixed fuel factor by approximately 24% to reflect reduced fuel expenses primarily related to a reduction in the price of natural gas used to generate power. The over-recovered balance was below the PUCT's materiality threshold. The reduction in the fixed fuel factor was effective on an interim basis May 1, 2015 and approved by the PUCT on May 20, 2015. As of March 31, 2016, the Company had over-recovered fuel costs in the amount of $5.2 million for the Texas jurisdiction.

Fuel Reconciliation Proceeding. Pursuant to the 2012 Texas retail rate settlement discussed above, on September 27, 2013, the Company filed an application with the PUCT, designated as PUCT Docket No. 41852, to reconcile $545.3 million of fuel and purchased power expenses incurred during the 45-month period from July 1, 2009 through March 31, 2013. A settlement was reached and a final order was issued by the PUCT on July 11, 2014 with no significant adjustments. The PUCT's final order completes the regulatory review and reconciliation of the Company's fuel expenses for the period through March 31, 2013. The Company is required to file an application by the end of the third quarter of 2016 for fuel reconciliation of the Company's fuel expenses for the period through March 31, 2016.

Montana Power Station ("MPS") Approvals. The Company has received a Certificate of Convenience and Necessity ("CCN") from the PUCT to construct four natural gas fired generating units at MPS in El Paso County, Texas. The Company also obtained air permits from the Texas Commission on Environmental Quality (the "TCEQ") and the U.S. Environmental Protection Agency (the "EPA"). MPS Units 1 and 2 and associated transmission lines and common facilities were completed and placed into service in March 2015. MPS Unit 3 was completed and placed into service on May 3, 2016.

Community Solar. On June 8, 2015, the Company filed a petition with the PUCT to initiate a community solar program to include construction and ownership of a 3 MW solar photovoltaic system located at MPS. Participation will be on a voluntary basis, and customers will contract for a set capacity (kW) amount and receive all energy produced. This case was assigned PUCT Docket No. 44800. The Company has presented settlement documents to the other parties and the other parties are in the process of evaluating them.

Four Corners Generating Station ("Four Corners"). On February 17, 2015, the Company and Arizona Public Service Company ("APS") entered into an asset purchase agreement (the "Purchase and Sale Agreement") providing for the purchase by APS of the Company's interests in Four Corners. The Purchase and Sale Agreement included a projected cash purchase price which will be equal to the net book value of our interest in Four Corners at the date of close. The net book value at June 30, 2016 is expected to approximate $29 million. The Company will also be reimbursed for certain undepreciated capital expenditures, that are projected to approximate $5 million at June 30, 2016. The purchase price will be adjusted downward to reflect APS's assumption of the Company's obligation to pay for future plant decommissioning and mine reclamation expenses estimated at July 6, 2016 to be $7.0 million and $19.3 million, respectively.

On June 10, 2015, the Company filed an application in Texas requesting reasonableness and public interest findings and certain rate and accounting findings related to the Purchase and Sale Agreement. The anticipated closing date of the sale is July 6, 2016, pending regulatory approval. This case was assigned PUCT Docket No. 44805. On January 11, 2016, the PUCT referred the case to the State Office of Administrative Hearings ("SOAH") for an administrative hearing. On February 5, 2016, an administrative law judge ("ALJ") of the SOAH issued an order adopting a procedural schedule. The procedural schedule calls for a hearing on the merits to be held on October 6-7, 2016. At March 31, 2016, the regulatory asset associated with mine reclamation costs for our Texas jurisdiction approximated $7.4 million. At the PUCT's February 11, 2016 open meeting, Commissioners discussed whether the Company's requests in this docket should instead be addressed in a rate case. On February 11, 2016, the PUCT issued its Order Requesting Briefing on Threshold Legal/Policy Issues, seeking briefs from the parties on the issue "Should the Commission dismiss this docket?" Such briefs were filed January 25, 2016. In a March 23, 2016 order, the PUCT determined not to dismiss the reasonableness and public interest issues in this docket but to consider the requested rate and accounting findings, including mine reclamation costs, in the Company's next rate case, which is expected to be filed in early 2017.

The Company currently continues to recover its mine reclamation costs in Texas under previous orders and decisions of the PUCT. If any future determinations made by our regulators result in changes to how existing regulatory assets or previously incurred costs for Four Corners are recovered in rates, any such changes would be recognized only when it becomes probable future cash flows will change as a result of such regulatory actions.

Other Required Approvals. The Company has obtained other required approvals for tariffs and approvals as required by the Public Utility Regulatory Act (the "PURA") and the PUCT.

New Mexico Regulatory Matters

2009 New Mexico Stipulation. On December 10, 2009, the NMPRC issued a final order conditionally approving the stipulated rates in NMPRC Case No. 09-00171-UT. The stipulated rates went into effect with January 2010 bills. The stipulated rates provide for an Efficient Use of Energy Factor Rate Rider to recover energy efficiency expenditures which are updated annually for adjustment to the recovery factors.

2015 New Mexico Rate Case Filing. On May 11, 2015, the Company filed with the NMPRC in Case No. 15-00127-UT, for an annual increase in non-fuel base rates of approximately $8.6 million or 7.1%. The request includes recovery of new plant placed into service since the last time rates were adjusted in 2009. The filing also requests an annual reduction of $15.4 million, or 21.5%, for fuel and purchased power costs recovered in base rates. The reduction in fuel and purchased power rates reflects reduced fuel prices and improvements in system heat rates due to new generating unit additions. Subsequently, the Company reduced its requested increase in non-fuel base rates to approximately $6.4 million. On February 16, 2016, the Hearing Examiner issued a Recommended Decision to the NMPRC proposing an annual increase in non-fuel base rates of approximately $640 thousand. The Company filed exceptions to the Recommended Decision to be considered by the NMPRC. During the open meeting on May 4, 2016, the NMPRC again extended the suspension period until June 10, 2016, by which time the NMPRC is expected to issue a final order. Approximately 24% of the Company's customers are in New Mexico. The Company cannot predict the outcome of the rate case at this time.

Fuel and Purchased Power Costs. Fuel and purchased power costs are recovered through base rates and a Fuel and Purchased Power Cost Adjustment Clause (the "FPPCAC") that accounts for changes in the costs of fuel relative to the amount included in base rates. On January 8, 2014, the NMPRC approved the continuation of the FPPCAC without modification in NMPRC Case No. 13-00380-UT. Fuel and purchased power costs are reconciled to actual costs on a monthly basis and recovered or refunded to customers the second succeeding month. The Company recovers costs related to Palo Verde Unit 3 capacity and energy in New Mexico through the FPPCAC as purchased power using a proxy market price approved in the 2014 FPPCAC continuation. At March 31, 2016, the Company had a net fuel over-recovery balance of $2.8 million in New Mexico.

Montana Power Station Approvals. The Company has received a CCN from the NMPRC to construct four units at MPS and the associated transmission lines. The Company also obtained all necessary air permits from the TCEQ and the EPA. A final order in NMPRC Case No. 13-00297-UT approving the CCN for MPS Units 3 and 4 was issued on June 11, 2014. MPS Units 1 and 2 and MPS to Caliente and MPS In & Out transmission lines were completed and placed into service in March 2015. MPS Unit 3 was completed and placed into service on May 3, 2016.

Four Corners. On February 17, 2015, the Company and APS entered into the Purchase and Sale Agreement providing for the purchase by APS of the Company's interests in Four Corners. On April 27, 2015, the Company filed an application requesting all necessary regulatory approvals to sell its ownership interest in Four Corners. The anticipated closing date of the sale is July 6, 2016, pending regulatory approval. This case was assigned NMPRC Case No. 15-00109-UT. On February 2, 2016, the Company filed a joint stipulation with the NMPRC reflecting a settlement agreement among the Commission Utility Division Staff, the Company and the New Mexico Attorney General proposing approval of abandonment and sale of its seven percent minority ownership interest in Four Corners Units 4 and 5 and common facilities to APS. An addendum to the joint stipulation was subsequently filed and the joint stipulation is unopposed. A hearing in the case was held on February 16, 2016, and the Hearing Examiner issued a Certification of Stipulation on April 22, 2016 recommending approval of the joint stipulation without modification. A NMPRC final order is expected in the first half of 2016. Based on the joint stipulation and addendum, no significant gain or loss is expected to be realized upon closing of the sale.

5 MW Holloman Air Force Base ("HAFB") Facility CCN. On June 15, 2015, the Company filed a petition with the NMPRC requesting CCN authorization to construct a 5 MW solar-powered generation facility to be located at HAFB in the Company's service territory in New Mexico. The new facility will be a dedicated Company-owned resource serving HAFB. This case was assigned NMPRC Case No. 15-00185-UT. On October 7, 2015, the NMPRC issued a Final Order accepting the Hearing Examiner’s Recommended Decision to approve the CCN, as modified. The Company and HAFB are in discussions for a power sales agreement for the facility to replace the existing load retention agreement.

Issuance of Long-Term Debt and Guarantee of Debt. On October 7, 2015, the Company received approval in NMPRC Case No. 15-00280-UT to issue up to $310 million in new long-term debt; and to guarantee the issuance of up to $65 million of new debt by Rio Grande Resources Trust ("RGRT") to finance future purchases of nuclear fuel and to refinance existing nuclear fuel debt obligations. This approval supersedes prior approvals. Under this authorization, on March 24, 2016, the Company issued $150 million in aggregate principal amount of 5.00% Senior Notes due December 1, 2044. The net proceeds from the issuance of these senior notes, after deducting the underwriters' commission, were $158.1 million. These proceeds include accrued interest of $2.4 million and a $7.1 million premium before expenses. These senior notes constitute an additional issuance of the Company's 5.00% Senior Notes due 2044, of which $150 million was previously issued on December 1, 2014, for a total principal amount outstanding of $300 million.

Other Required Approvals. The Company has obtained other required approvals for other tariffs, securities transactions, recovery of energy efficiency costs through a base rate rider and other approvals as required by the NMPRC.

Federal Regulatory Matters

Four Corners. On June 26, 2015, APS filed an application requesting authorization from FERC to purchase 100% of the Company’s ownership interest in Units 4 and 5 of Four Corners and the associated transmission interconnection facilities and rights. On December 22, 2015, FERC issued an order approving the proposed transaction.

Public Service Company of New Mexico ("PNM") Transmission Rate Case. On December 31, 2012, PNM filed with FERC to change its method of transmission rate recovery for its transmission delivery services from stated rates to formula rates. The Company takes transmission service from PNM and is among the PNM transmission customers affected by PNM's shift to formula rates. On March 1, 2013, the FERC issued an order rejecting in part PNM's filing, and establishing settlement judge and hearing procedures. On March 20, 2015, PNM filed with FERC a settlement agreement and offer of settlement resolving all issues set for hearing in the proceeding. On March 25, 2015, the Chief Judge issued an order granting PNM's motion to implement the settled rates. On March 17, 2016, FERC issued an order approving the settlement.

Revolving Credit Facility; Issuance of Long-Term Debt and Guarantee of Debt. On October 19, 2015, the FERC issued an order in Docket No. ES15-66-000 approving the Company’s filing to issue short-term debt under its existing revolving credit facility ("RCF") up to $400 million outstanding at any time, to issue up to $310 million in long-term debt, and to guarantee the issuance of up to $65 million of new long-term debt by RGRT to finance future nuclear fuel purchases. The authorization is effective from November 15, 2015 through November 15, 2017. This approval supersedes prior approvals. Under this authorization, on March 24, 2016, the Company issued $150 million in aggregate principal amount of 5.00% Senior Notes due December 1, 2044. The net proceeds from the issuance of these senior notes, after deducting the underwriters' commission, were $158.1 million. These proceeds include accrued interest of $2.4 million and a $7.1 million premium before expenses. These senior notes constitute an additional issuance of the Company's 5.00% Senior Notes due 2044, of which $150 million was previously issued on December 1, 2014, for a total principal amount outstanding of $300 million.

Other Required Approvals. The Company has obtained required approvals for rates and tariffs, securities transactions and other approvals as required by the FERC.