Regulation	9 Months Ended
Sep. 30, 2017
Regulated Operations [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 Energy 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 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 ("2015 Texas Retail Rate Case"). On July 21, 2016, the parties to PUCT Docket No. 44941 filed the Joint Motion to Implement Uncontested Amended and Restated Stipulation and Agreement which was unopposed by the parties ("2016 Unopposed Settlement"). On August 25, 2016, the PUCT approved the 2016 Unopposed Settlement and issued its final order in Docket No. 44941 ("2016 PUCT Final Order"), as proposed. The 2016 PUCT Final Order provided for: (i) an annual non-fuel base rate increase, lower annual depreciation expense, a revised return on equity for allowance for funds used during construction ("AFUDC") purposes, and the inclusion of substantially all new plant in service in rate base; (ii) an additional annual non-fuel base rate increase of $3.7 million related to Four Corners costs, which was collected through a surcharge that terminated on July 11, 2017; (iii) removing the separate rate treatment for residential customers with solar systems that the Company had proposed in its August 10, 2015 filing; (iv) allowing the Company to recover $3.1 million in rate case expenses through a separate surcharge; and (v) allowing the Company to recover revenues associated with the relate back of rates to consumption on and after January 12, 2016 through March 31, 2016 through a separate surcharge. Interim rates associated with the annual non-fuel base rate increase became effective on April 1, 2016. The additional surcharges associated with the incremental Four Corners costs, rate case expenses and the relate back of rates to consumption on and after January 12, 2016 through March 31, 2016 were implemented on October 1, 2016. For financial reporting purposes, the Company deferred any recognition of the Company's request in its 2015 Texas Retail Rate Case until it received the 2016 PUCT Final Order on August 25, 2016. Accordingly, it reported in the third quarter of 2016 the cumulative effect of the 2016 PUCT Final Order which related back to January 12, 2016. 2017 Texas Retail Rate Case Filing. On February 13, 2017, the Company filed with the City of El Paso, other municipalities incorporated in the Company's Texas service territory and the PUCT in Docket No. 46831, a request for an increase in non-fuel base revenues of approximately $42.5 million. On May 16, 2017, the Company filed a motion to sever rate case expense issues from the main rate case. The request was approved by the Administrative Law Judges ("ALJs"), initiating Docket No. 47228, on June 5, 2017. On July 21, 2017, the Company filed its rebuttal testimony modifying the requested increase to $39.2 million. The decrease from the original request related primarily to the transfer of the recovery of $3.0 million of the rate case expenses to a separate proceeding as noted above. The Company requested, pursuant to its statutory right, to have its new rates relate back for consumption on and after July 18, 2017, which was the 155th day after the filing of the rate case. The difference in rates that would have been billed will be surcharged or refunded to customers after the PUCT's final order is issued in Docket No. 46831. The PUCT has the authority to require the Company to surcharge or refund such difference over a period not to exceed 18 months. On November 2, 2017 the Joint Motion to Implement Uncontested Stipulation and Agreement ("2017 Unopposed Settlement") was filed with the ALJs for the Company's rate case pending in Docket No. 46831. Key terms of the 2017 Unopposed Settlement include: (i) an annual non-fuel base rate increase of $14.5 million; (ii) a return on equity of 9.65%; (iii) a determination that all new plant in service was prudent and used and useful and therefore is included in rate base; and (iv) allowing the Company to recover approximately $3.4 million in rate case expenses incurred through August 2017, through a separate surcharge over a three-year period. The 2017 Unopposed Settlement also establishes baseline revenue requirements for recovery of future transmission and distribution investment costs and includes a minimum monthly bill of $30.00 for new residential customers with distributed generation, such as private rooftop solar. Additionally, the 2017 Unopposed Settlement allows for the annual recovery of $2.1 million of nuclear decommissioning funding and establishes annual depreciation expense that is approximately $1.9 million lower than the annual amount requested by the Company in its initial filing. The filing with the ALJs requested that they return the case to the PUCT for approval. A final PUCT order ("Final Order") in the 2017 Texas retail rate case is expected to be issued in the fourth quarter of 2017. The Company did not recognize the impacts of the 2017 Unopposed Settlement in the Statements of Operations for the third quarter of 2017 because the Final Order has not yet been issued by the PUCT. At this time, the Company believes the revenue and other impacts of the 2017 Unopposed Settlement for financial reporting purposes will be recognized during the fourth quarter of 2017, which is when the Final Order is expected to be issued by the PUCT. Regardless of when the Final Order is issued by the PUCT, the new rates are expected to relate back to consumption on or after July 18, 2017. Energy Efficiency Cost Recovery Factor. On May 1, 2017, the Company filed its annual application, which was assigned PUCT Docket No. 47125, to establish its energy efficiency cost recovery factor for 2018. In addition to projected energy efficiency costs for 2018 and a true-up to prior year actual costs, the Company requested approval of a $1.0 million bonus for the 2016 energy efficiency program results in accordance with PUCT rules. On August 2, 2017, the Company filed an agreed motion to request suspension of the schedule in the case to allow the parties to pursue settlement. The hearing on the merits of this case was scheduled to begin on August 15, 2017, but has been continued pending possible settlement. The Company cannot predict the outcome of this matter at this time. Fuel and Purchased Power Costs. On November 30, 2016, the Company filed a request, which was assigned PUCT Docket No. 46610, to increase its fixed fuel factor by approximately 28.8% to reflect increased fuel expenses primarily related to an increase in the price of natural gas used to generate power. The increase in the fixed fuel factor was effective on an interim basis January 1, 2017 and approved by the PUCT on January 10, 2017. As of September 30, 2017, the Company had over-recovered fuel costs in the amount of $1.1 million for the Texas jurisdiction. On October 13, 2017, the Company filed a request to decrease the Texas fixed fuel factor by approximately 19% to reflect decreased fuel expenses primarily related to a decrease in the price of natural gas used to generate power. The decrease in the Texas fixed fuel factor became effective beginning with the November 2017 billing month and will continue thereafter until changed by the PUCT. Fuel Reconciliation Proceeding. On September 27, 2016, the Company filed an application with the PUCT, designated as PUCT Docket No. 46308, to reconcile $436.6 million of Texas fuel and purchased power expenses incurred during the period of April 1, 2013 through March 31, 2016. On June 29, 2017, the PUCT approved a settlement in this proceeding. The settlement provides for the reconciliation of fuel and purchased power costs incurred from April 1, 2013 through March 31, 2016. Additionally, the settlement modifies and tightens the Palo Verde Nuclear Generating Station ("Palo Verde") performance rewards measurement bands beginning with the 2018 performance period. The financial results for the nine months ended September 30, 2017 include a $5.0 million, pre-tax increase to income reflecting the settlement of the Texas fuel reconciliation proceeding. This amount includes Palo Verde performance rewards associated with the 2013 to 2015 performance periods net of disallowed fuel and purchased power costs as approved in the settlement. As of September 30, 2017, Texas jurisdictional fuel and purchased power costs subject to a future Texas fuel reconciliation are approximately $223.3 million. Community Solar. On June 8, 2015, the Company filed a petition with the PUCT to initiate a community solar program that includes the construction and ownership of a 3 MW solar photovoltaic system located at the Company's Montana Power Station. 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 filed a settlement agreement among all parties on July 1, 2016 approving the program, and the PUCT approved the settlement agreement and program on September 1, 2016. On April 19, 2017, the Company announced that the entire 3 MW program was fully subscribed by approximately 1,500 Texas customers. The Community Solar facility began commercial operation on May 31, 2017. Four Corners Generating Station. On February 17, 2015, the Company and APS entered into an asset purchase agreement ("Purchase and Sale Agreement") providing for the sale of the Company's interest in Four Corners to APS. The sale of the Company's interest in Four Corners closed on July 6, 2016. 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. This case was assigned PUCT Docket No. 44805. Subsequent to the filing of the application, the case was subject to numerous procedural matters, including a March 23, 2016 order in which 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 coal mine reclamation costs, in a rate case proceeding. On September 1, 2016, a motion by parties in the proceeding to suspend the procedural schedule in order to pursue settlement was approved. On March 3, 2017, the Company filed a Joint Motion to Implement Stipulation and Agreement ("Stipulation and Agreement"), and PUCT Staff filed its recommendation that the Company’s disposition of its interest in Four Corners was reasonable and consistent with the public interest. Additionally, the signatories of the Stipulation and Agreement agreed to support the recovery of the Company's Four Corners decommissioning costs in the 2017 Texas retail rate case. A final order approving the Stipulation and Agreement was adopted by the PUCT on March 30, 2017. Other Required Approvals. The Company has obtained other required approvals for tariffs and approvals required by the Public Utility Regulatory Act ("PURA") and the PUCT. New Mexico Regulatory Matters 2015 New Mexico Rate Case Filing. On May 11, 2015, the Company filed a request with the NMPRC, in Case No. 15-00127-UT, for an annual increase in non-fuel base rates. On June 8, 2016, the NMPRC issued its final order in Case No. 15-00127-UT ("NMPRC Final Order"), which approved an annual increase in non-fuel base rates of approximately $0.6 million, an increase of approximately $0.5 million in other service fees and a decrease in the Company's allowed return on equity to 9.48%. The NMPRC Final Order concluded that all of the Company's new plant in service was reasonable and necessary and therefore would be recoverable in rates. The Company's rates were approved by the NMPRC effective July 1, 2016 and implemented at such time. Future New Mexico Rate Case Filing. NMPRC Case No. 15-00109-UT required the Company to make a rate filing in New Mexico in the second quarter of 2017 using a historical test year ended December 31, 2016. On March 24, 2017, the Company, NMPRC Utility Division Staff and the New Mexico Attorney General filed a Joint Motion to Modify Filing Date Stated in Final Order requesting that the rate filing date be changed to no later than July 31, 2019, using the appropriate historical test year period. The joint request was approved by the NMPRC on April 12, 2017. Fuel and Purchased Power Costs. Historically, fuel and purchased power costs were recovered through base rates and a Fuel and Purchased Power Cost Adjustment Clause ("FPPCAC") that accounts for changes in the costs of fuel relative to the amount included in base rates. Effective July 1, 2016, with the implementation of the final order in Case No. 15-00127-UT, fuel and purchased power costs are no longer recovered through base rates but are recovered through the FPPCAC. The Company's request to reconcile its fuel and purchased power costs for the period January 1, 2013 through December 31, 2014 was approved in Case No. 15-00127-UT. New Mexico jurisdictional costs subject to prudence review are costs from January 1, 2015 through September 30, 2017 that total approximately $160.9 million. At September 30, 2017, the Company had a net fuel over-recovery balance of approximately $1.9 million in New Mexico. 5 MW Holloman Air Force Base ("HAFB") Facility Certificate of Convenience and Necessity ("CCN"). On October 7, 2015, in NMPRC Case No. 15-00185-UT, the NMPRC issued a final order approving a CCN for a 5 MW solar power generation facility located on HAFB in the Company's service territory in New Mexico. The Company and HAFB negotiated a retail contract, which includes power sales agreement for the facility, to replace the existing load retention agreement which was approved by final order issued October 5, 2016 in NMPRC Case No. 16-00224-UT. Construction of the solar generation facility is expected to be completed in the third quarter of 2018. New Mexico Efficient Use of Energy Recovery Factor. On July 1, 2016, the Company filed its annual application requesting approval of its 2017 Energy Efficiency and Load Management Plan and to establish energy efficiency cost recovery factors for 2017. In addition to projected energy efficiency costs for 2017, the Company requested approval of a $0.4 million incentive for 2017 energy efficiency programs in accordance with NMPRC rules. This case was assigned Case No. 16-00185-UT. On February 22, 2017, the NMPRC issued a Final Order approving the Company’s 2017 Energy Efficiency and Load Management Plan and authorizing recovery in 2017 of a base incentive of $0.4 million. The Company’s energy efficiency cost recovery factors were approved and effective in customer bills beginning on March 1, 2017. On July 1, 2016, the Company filed its 2015 Annual Report for Energy Efficiency Programs, which included an incentive for verified 2015 program performance of $0.3 million, which was approved in Case No. 13-00176-UT. The Company recorded the $0.3 million approved incentive in operating revenues in the first quarter of 2017. In addition, on June 30, 2017, the Company filed its 2016 Annual Report for Energy Efficiency Programs, which included an incentive for verified 2016 program performance of $0.4 million which was approved in Case No. 13-00176-UT. The Company recorded the $0.4 million approved incentive in operating revenues in the third quarter of 2017. Revolving Credit Facility, Issuance of Long-Term Debt, and Securities Financing. On October 7, 2015, the Company received approval from the NMPRC to guarantee the issuance of up to $65.0 million of long-term debt by the Rio Grande Resources Trust ("RGRT") to finance future purchases of nuclear fuel and to refinance existing nuclear fuel debt obligations, for which the approval remains effective. On October 4, 2017, the Company received additional approval in NMPRC Case No. 17-00217-UT to amend and extend its Revolving Credit Facility ("RCF"), issue up to $350.0 million in long-term debt and to redeem and refinance the $63.5 million 2009 Series A 7.25% Pollution Control Bonds and the $37.1 million 2009 Series B 7.25% Pollution Control Bonds, which are subject to optional redemption in 2019. The NMPRC approval to issue $350.0 million in long-term debt supersedes prior approval. Other Required Approvals. The Company has obtained other required approvals for other tariffs and other approvals as required by the NMPRC. Federal Regulatory Matters Revolving Credit Facility, Issuance of Long-Term Debt, Securities Financing, and Guarantee of Debt. On October 31, 2017, the FERC issued an order in Docket No. ES17-54-000 approving the Company's filing to (i) amend and extend the RCF; (ii) issue up to $350.0 million in long-term debt; (iii) guarantee the issuance of up to $65.0 million of long-term debt by the RGRT; and (iv) redeem and refinance the $63.5 million 2009 Series A 7.25% Pollution Control Bonds and the $37.1 million 2009 Series B 7.25% Pollution Control Bonds, which are subject to optional redemption in 2019. The order also approves the Company's request to continue to utilize the Company's existing RCF with the ability to amend and extend at a future date. The authorization is effective from November 15, 2017 through November 14, 2019 and supersedes prior approvals. The Company has obtained required approvals for rates, tariffs 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 Energy 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

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 ("2015 Texas Retail Rate Case").

On July 21, 2016, the parties to PUCT Docket No. 44941 filed the Joint Motion to Implement Uncontested Amended and Restated Stipulation and Agreement which was unopposed by the parties ("2016 Unopposed Settlement"). On August 25, 2016, the PUCT approved the 2016 Unopposed Settlement and issued its final order in Docket No. 44941 ("2016 PUCT Final Order"), as proposed. The 2016 PUCT Final Order provided for: (i) an annual non-fuel base rate increase, lower annual depreciation expense, a revised return on equity for allowance for funds used during construction ("AFUDC") purposes, and the inclusion of substantially all new plant in service in rate base; (ii) an additional annual non-fuel base rate increase of $3.7 million related to Four Corners costs, which was collected through a surcharge that terminated on July 11, 2017; (iii) removing the separate rate treatment for residential customers with solar systems that the Company had proposed in its August 10, 2015 filing; (iv) allowing the Company to recover $3.1 million in rate case expenses through a separate surcharge; and (v) allowing the Company to recover revenues associated with the relate back of rates to consumption on and after January 12, 2016 through March 31, 2016 through a separate surcharge.

Interim rates associated with the annual non-fuel base rate increase became effective on April 1, 2016. The additional surcharges associated with the incremental Four Corners costs, rate case expenses and the relate back of rates to consumption on and after January 12, 2016 through March 31, 2016 were implemented on October 1, 2016.

For financial reporting purposes, the Company deferred any recognition of the Company's request in its 2015 Texas Retail Rate Case until it received the 2016 PUCT Final Order on August 25, 2016. Accordingly, it reported in the third quarter of 2016 the cumulative effect of the 2016 PUCT Final Order which related back to January 12, 2016.

2017 Texas Retail Rate Case Filing. On February 13, 2017, the Company filed with the City of El Paso, other municipalities incorporated in the Company's Texas service territory and the PUCT in Docket No. 46831, a request for an increase in non-fuel base revenues of approximately $42.5 million. On May 16, 2017, the Company filed a motion to sever rate case expense issues from the main rate case. The request was approved by the Administrative Law Judges ("ALJs"), initiating Docket No. 47228, on June 5, 2017.

On July 21, 2017, the Company filed its rebuttal testimony modifying the requested increase to $39.2 million. The decrease from the original request related primarily to the transfer of the recovery of $3.0 million of the rate case expenses to a separate proceeding as noted above. The Company requested, pursuant to its statutory right, to have its new rates relate back for consumption on and after July 18, 2017, which was the 155th day after the filing of the rate case. The difference in rates that would have been billed will be surcharged or refunded to customers after the PUCT's final order is issued in Docket No. 46831. The PUCT has the authority to require the Company to surcharge or refund such difference over a period not to exceed 18 months.

On November 2, 2017 the Joint Motion to Implement Uncontested Stipulation and Agreement ("2017 Unopposed Settlement") was filed with the ALJs for the Company's rate case pending in Docket No. 46831. Key terms of the 2017 Unopposed Settlement include: (i) an annual non-fuel base rate increase of $14.5 million; (ii) a return on equity of 9.65%; (iii) a determination that all new plant in service was prudent and used and useful and therefore is included in rate base; and (iv) allowing the Company to recover approximately $3.4 million in rate case expenses incurred through August 2017, through a separate surcharge over a three-year period. The 2017 Unopposed Settlement also establishes baseline revenue requirements for recovery of future transmission and distribution investment costs and includes a minimum monthly bill of $30.00 for new residential customers with distributed generation, such as private rooftop solar. Additionally, the 2017 Unopposed Settlement allows for the annual recovery of $2.1 million of nuclear decommissioning funding and establishes annual depreciation expense that is approximately $1.9 million lower than the annual amount requested by the Company in its initial filing.

The filing with the ALJs requested that they return the case to the PUCT for approval. A final PUCT order ("Final Order") in the 2017 Texas retail rate case is expected to be issued in the fourth quarter of 2017.

The Company did not recognize the impacts of the 2017 Unopposed Settlement in the Statements of Operations for the third quarter of 2017 because the Final Order has not yet been issued by the PUCT. At this time, the Company believes the revenue and other impacts of the 2017 Unopposed Settlement for financial reporting purposes will be recognized during the fourth quarter of 2017, which is when the Final Order is expected to be issued by the PUCT. Regardless of when the Final Order is issued by the PUCT, the new rates are expected to relate back to consumption on or after July 18, 2017.

Energy Efficiency Cost Recovery Factor. On May 1, 2017, the Company filed its annual application, which was assigned PUCT Docket No. 47125, to establish its energy efficiency cost recovery factor for 2018. In addition to projected energy efficiency costs for 2018 and a true-up to prior year actual costs, the Company requested approval of a $1.0 million bonus for the 2016 energy efficiency program results in accordance with PUCT rules. On August 2, 2017, the Company filed an agreed motion to request suspension of the schedule in the case to allow the parties to pursue settlement. The hearing on the merits of this case was scheduled to begin on August 15, 2017, but has been continued pending possible settlement. The Company cannot predict the outcome of this matter at this time.

Fuel and Purchased Power Costs. On November 30, 2016, the Company filed a request, which was assigned PUCT Docket No. 46610, to increase its fixed fuel factor by approximately 28.8% to reflect increased fuel expenses primarily related to an increase in the price of natural gas used to generate power. The increase in the fixed fuel factor was effective on an interim basis January 1, 2017 and approved by the PUCT on January 10, 2017. As of September 30, 2017, the Company had over-recovered fuel costs in the amount of $1.1 million for the Texas jurisdiction. On October 13, 2017, the Company filed a request to decrease the Texas fixed fuel factor by approximately 19% to reflect decreased fuel expenses primarily related to a decrease in the price of natural gas used to generate power. The decrease in the Texas fixed fuel factor became effective beginning with the November 2017 billing month and will continue thereafter until changed by the PUCT.

Fuel Reconciliation Proceeding. On September 27, 2016, the Company filed an application with the PUCT, designated as PUCT Docket No. 46308, to reconcile $436.6 million of Texas fuel and purchased power expenses incurred during the period of April 1, 2013 through March 31, 2016. On June 29, 2017, the PUCT approved a settlement in this proceeding. The settlement provides for the reconciliation of fuel and purchased power costs incurred from April 1, 2013 through March 31, 2016. Additionally, the settlement modifies and tightens the Palo Verde Nuclear Generating Station ("Palo Verde") performance rewards measurement bands beginning with the 2018 performance period. The financial results for the nine months ended September 30, 2017 include a $5.0 million, pre-tax increase to income reflecting the settlement of the Texas fuel reconciliation proceeding. This amount includes Palo Verde performance rewards associated with the 2013 to 2015 performance periods net of disallowed fuel and purchased power costs as approved in the settlement. As of September 30, 2017, Texas jurisdictional fuel and purchased power costs subject to a future Texas fuel reconciliation are approximately $223.3 million.

Community Solar. On June 8, 2015, the Company filed a petition with the PUCT to initiate a community solar program that includes the construction and ownership of a 3 MW solar photovoltaic system located at the Company's Montana Power Station. 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 filed a settlement agreement among all parties on July 1, 2016 approving the program, and the PUCT approved the settlement agreement and program on September 1, 2016. On April 19, 2017, the Company announced that the entire 3 MW program was fully subscribed by approximately 1,500 Texas customers. The Community Solar facility began commercial operation on May 31, 2017.

Four Corners Generating Station. On February 17, 2015, the Company and APS entered into an asset purchase agreement ("Purchase and Sale Agreement") providing for the sale of the Company's interest in Four Corners to APS. The sale of the Company's interest in Four Corners closed on July 6, 2016.

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. This case was assigned PUCT Docket No. 44805. Subsequent to the filing of the application, the case was subject to numerous procedural matters, including a March 23, 2016 order in which 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 coal mine reclamation costs, in a rate case proceeding. On September 1, 2016, a motion by parties in the proceeding to suspend the procedural schedule in order to pursue settlement was approved. On March 3, 2017, the Company filed a Joint Motion to Implement Stipulation and Agreement ("Stipulation and Agreement"), and PUCT Staff filed its recommendation that the Company’s disposition of its interest in Four Corners was reasonable and consistent with the public interest. Additionally, the signatories of the Stipulation and Agreement agreed to support the recovery of the Company's Four Corners decommissioning costs in the 2017 Texas retail rate case. A final order approving the Stipulation and Agreement was adopted by the PUCT on March 30, 2017.

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

New Mexico Regulatory Matters

2015 New Mexico Rate Case Filing. On May 11, 2015, the Company filed a request with the NMPRC, in Case No. 15-00127-UT, for an annual increase in non-fuel base rates. On June 8, 2016, the NMPRC issued its final order in Case No. 15-00127-UT ("NMPRC Final Order"), which approved an annual increase in non-fuel base rates of approximately $0.6 million, an increase of approximately $0.5 million in other service fees and a decrease in the Company's allowed return on equity to 9.48%. The NMPRC Final Order concluded that all of the Company's new plant in service was reasonable and necessary and therefore would be recoverable in rates. The Company's rates were approved by the NMPRC effective July 1, 2016 and implemented at such time.

Future New Mexico Rate Case Filing. NMPRC Case No. 15-00109-UT required the Company to make a rate filing in New Mexico in the second quarter of 2017 using a historical test year ended December 31, 2016. On March 24, 2017, the Company, NMPRC Utility Division Staff and the New Mexico Attorney General filed a Joint Motion to Modify Filing Date Stated in Final Order requesting that the rate filing date be changed to no later than July 31, 2019, using the appropriate historical test year period. The joint request was approved by the NMPRC on April 12, 2017.

Fuel and Purchased Power Costs. Historically, fuel and purchased power costs were recovered through base rates and a Fuel and Purchased Power Cost Adjustment Clause ("FPPCAC") that accounts for changes in the costs of fuel relative to the amount included in base rates. Effective July 1, 2016, with the implementation of the final order in Case No. 15-00127-UT, fuel and purchased power costs are no longer recovered through base rates but are recovered through the FPPCAC. The Company's request to reconcile its fuel and purchased power costs for the period January 1, 2013 through December 31, 2014 was approved in Case No. 15-00127-UT. New Mexico jurisdictional costs subject to prudence review are costs from January 1, 2015 through September 30, 2017 that total approximately $160.9 million. At September 30, 2017, the Company had a net fuel over-recovery balance of approximately $1.9 million in New Mexico.

5 MW Holloman Air Force Base ("HAFB") Facility Certificate of Convenience and Necessity ("CCN"). On October 7, 2015, in NMPRC Case No. 15-00185-UT, the NMPRC issued a final order approving a CCN for a 5 MW solar power generation facility located on HAFB in the Company's service territory in New Mexico. The Company and HAFB negotiated a retail contract, which includes power sales agreement for the facility, to replace the existing load retention agreement which was approved by final order issued October 5, 2016 in NMPRC Case No. 16-00224-UT. Construction of the solar generation facility is expected to be completed in the third quarter of 2018.

New Mexico Efficient Use of Energy Recovery Factor. On July 1, 2016, the Company filed its annual application requesting approval of its 2017 Energy Efficiency and Load Management Plan and to establish energy efficiency cost recovery factors for 2017. In addition to projected energy efficiency costs for 2017, the Company requested approval of a $0.4 million incentive for 2017 energy efficiency programs in accordance with NMPRC rules. This case was assigned Case No. 16-00185-UT. On February 22, 2017, the NMPRC issued a Final Order approving the Company’s 2017 Energy Efficiency and Load Management Plan and authorizing recovery in 2017 of a base incentive of $0.4 million. The Company’s energy efficiency cost recovery factors were approved and effective in customer bills beginning on March 1, 2017.

On July 1, 2016, the Company filed its 2015 Annual Report for Energy Efficiency Programs, which included an incentive for verified 2015 program performance of $0.3 million, which was approved in Case No. 13-00176-UT. The Company recorded the $0.3 million approved incentive in operating revenues in the first quarter of 2017. In addition, on June 30, 2017, the Company filed its 2016 Annual Report for Energy Efficiency Programs, which included an incentive for verified 2016 program performance of $0.4 million which was approved in Case No. 13-00176-UT. The Company recorded the $0.4 million approved incentive in operating revenues in the third quarter of 2017.

Revolving Credit Facility, Issuance of Long-Term Debt, and Securities Financing. On October 7, 2015, the Company received approval from the NMPRC to guarantee the issuance of up to $65.0 million of long-term debt by the Rio Grande Resources Trust ("RGRT") to finance future purchases of nuclear fuel and to refinance existing nuclear fuel debt obligations, for which the approval remains effective. On October 4, 2017, the Company received additional approval in NMPRC Case No. 17-00217-UT to amend and extend its Revolving Credit Facility ("RCF"), issue up to $350.0 million in long-term debt and to redeem and refinance the $63.5 million 2009 Series A 7.25% Pollution Control Bonds and the $37.1 million 2009 Series B 7.25% Pollution Control Bonds, which are subject to optional redemption in 2019. The NMPRC approval to issue $350.0 million in long-term debt supersedes prior approval.

Other Required Approvals. The Company has obtained other required approvals for other tariffs and other approvals as required by the NMPRC.

Federal Regulatory Matters

Revolving Credit Facility, Issuance of Long-Term Debt, Securities Financing, and Guarantee of Debt. On October 31, 2017, the FERC issued an order in Docket No. ES17-54-000 approving the Company's filing to (i) amend and extend the RCF; (ii) issue up to $350.0 million in long-term debt; (iii) guarantee the issuance of up to $65.0 million of long-term debt by the RGRT; and (iv) redeem and refinance the $63.5 million 2009 Series A 7.25% Pollution Control Bonds and the $37.1 million 2009 Series B 7.25% Pollution Control Bonds, which are subject to optional redemption in 2019. The order also approves the Company's request to continue to utilize the Company's existing RCF with the ability to amend and extend at a future date. The authorization is effective from November 15, 2017 through November 14, 2019 and supersedes prior approvals.

The Company has obtained required approvals for rates, tariffs and other approvals as required by the FERC.