Significant Accounting Policies and Responsibility for Financial Statements	3 Months Ended
Mar. 31, 2019
Accounting Policies [Abstract]
Significant Accounting Policies and Responsibility for Financial Statements	Significant Accounting Policies and Responsibility for Financial Statements Financial Statement Preparation In the opinion of management, the accompanying unaudited interim Condensed Consolidated Financial Statements reflect all normal and recurring accruals and adjustments that are necessary to present fairly the consolidated financial position at March 31, 2019 and December 31, 2018, and the consolidated results of operations, comprehensive income, and cash flows for the three months ended March 31, 2019 and 2018. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could ultimately differ from those estimated. Weather causes the Company’s results of operations to be seasonal in nature and the results of operations presented in the accompanying Condensed Consolidated Financial Statements are not necessarily representative of operations for an entire year. The Notes to Condensed Consolidated Financial Statements include disclosures for PNMR, PNM, and TNMP. This report uses the term “Company” when discussing matters of common applicability to PNMR, PNM, and TNMP. Discussions regarding only PNMR, PNM, or TNMP are so indicated. Certain amounts in the 2018 Condensed Consolidated Financial Statements and Notes thereto have been reclassified to conform to the 2019 financial statement presentation. These Condensed Consolidated Financial Statements are unaudited. Certain information and note disclosures normally included in the annual audited Consolidated Financial Statements have been condensed or omitted, as permitted under the applicable rules and regulations. Readers of these financial statements should refer to PNMR’s, PNM’s, and TNMP’s audited Consolidated Financial Statements and Notes thereto that are included in their respective 2018 Annual Reports on Form 10-K. GAAP defines subsequent events as events or transactions that occur after the balance sheet date but before financial statements are issued or are available to be issued. Based on their nature, magnitude, and timing, certain subsequent events may be required to be reflected at the balance sheet date and/or required to be disclosed in the financial statements. The Company has evaluated subsequent events as required by GAAP. Principles of Consolidation The Condensed Consolidated Financial Statements of each of PNMR, PNM, and TNMP include their accounts and those of subsidiaries in which that entity owns a majority voting interest. PNM also consolidates Valencia (Note 6). PNM owns undivided interests in several jointly-owned power plants and records its pro-rata share of the assets, liabilities, and expenses for those plants. The agreements for the jointly-owned plants provide that if an owner were to default on its payment obligations, the non-defaulting owners would be responsible for their proportionate share of the obligations of the defaulting owner. In exchange, the non-defaulting owners would be entitled to their proportionate share of the generating capacity of the defaulting owner. There have been no such payment defaults under any of the agreements for the jointly-owned plants. PNMR shared services’ expenses, which represent costs that are primarily driven by corporate level activities, are charged to the business segments. These services are billed at cost and are reflected as general and administrative expenses in the business segments. Other significant intercompany transactions between PNMR, PNM, and TNMP include interest and income tax sharing payments, equity transactions, and interconnection billings (Note 15). All intercompany transactions and balances have been eliminated. Dividends on Common Stock Dividends on PNMR’s common stock are declared by the Board. The timing of the declaration of dividends is dependent on the timing of meetings and other actions of the Board. TNMP declared and paid cash dividends on common stock to PNMR of $10.7 million and $1.0 million in the three months ended March 31, 2019 and 2018. Investment in NM Renewable Development, LLC As discussed in Note 1 of the 2018 Annual Reports on Form 10-K, PNMR Development and AEP OnSite Partners created NMRD in September 2017 to pursue the acquisition, development, and ownership of renewable energy generation projects, primarily in the state of New Mexico. NMRD’s current renewable energy capacity in operation is 33.9 MW. PNMR Development and AEP OnSite Partners each have a 50% ownership interest in NMRD. The investment in NMRD is accounted for using the equity method of accounting because PNMR’s ownership interest results in significant influence, but not control, over NMRD and its operations. In the three months ended March 31, 2019 and 2018, PNMR Development made cash contributions of $7.0 million and $5.0 million to NMRD to be used primarily for its construction activities. For the three months ended March 31, 2019 and 2018, NMRD had revenues of $0.7 million and $0.4 million and net earnings (losses) of $(0.1) million and $0.1 million. At March 31, 2019 and December 31, 2018, NMRD had $8.0 million and $2.6 million of current assets, $65.2 million and $50.8 million of property, plant, and equipment and other assets, $6.1 million and $0.2 million of current liabilities, and $67.1 million and $53.2 million of owners’ equity. New Accounting Pronouncements Information concerning recently issued accounting pronouncements that have not been adopted by the Company is presented below. The Company does not expect difficulty in adopting these standards by their required effective dates. Accounting Standards Update 2016-13 – Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments In June 2016, the FASB issued ASU 2016-13, which changes the way entities recognize impairment of many financial assets, including accounts receivable and investments in certain debt securities, by requiring immediate recognition of estimated credit losses expected to occur over the remaining lives of the assets. In November 2018, the FASB clarified that receivables arising from operating leases are not within the scope of Topic 326 for assets measured at amortized costs. Instead, impairments of receivables arising from operating leases should be accounted for in accordance with Topic 842. The Company anticipates adopting ASU 2016-13 as of January 1, 2020, its required effective date. The Company is in the process of analyzing the impacts of this new standard, but does not anticipate it will have a significant impact on its financial statements. Accounting Standards Update 2017-04 – Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment In January 2017, the FASB issued ASU 2017-04 to simplify the annual goodwill impairment assessment process. Currently, the first step of a quantitative impairment test requires an entity to compare the fair value of each reporting unit containing goodwill with its carrying value (including goodwill). If as a result of this analysis, the entity concludes there is an indication of impairment in a reporting unit having goodwill, the entity is required to perform the second step of the impairment analysis, determining the amount of goodwill impairment to be recorded. The amount is calculated by comparing the implied fair value of the goodwill to its carrying amount. This exercise requires the entity to allocate the fair value determined in step one to the individual assets and liabilities of the reporting unit. Any remaining fair value would be the implied fair value of goodwill on the testing date. To the extent the recorded amount of goodwill of a reporting unit exceeds the implied fair value determined in step two, an impairment loss would be reflected in results of operations. ASU 2017-04 eliminates the second step of the impairment analysis. Accordingly, if the first step of a quantitative goodwill impairment analysis performed after adoption of ASU 2017-04 indicates that the fair value of a reporting unit is less than its carrying value, the goodwill of that reporting unit would be impaired to the extent of that difference. The Company anticipates it will adopt ASU 2017-04 for impairment testing after January 1, 2020, its required effective date, although early adoption is permitted. However, if there is an indication of potential impairment of goodwill as a result of an impairment assessment prior to 2020, the Company will evaluate the impact of ASU 2017-04 and could elect to early adopt this standard. Accounting Standards Update 2018-13 – Fair Value Measurements (Topic 820) Disclosure Framework: Changes to the Disclosure Requirements for Fair Value Measurements In August 2018, the FASB issued ASU 2018-13 to improve fair value disclosures. ASU 2018-13 eliminates certain disclosure requirements related to transfers between Levels 1 and 2 of the fair value hierarchy and the requirement to disclose the valuation process for Level 3 fair value measurements. ASU 2018-13 also amends certain disclosure requirements for investments measured at net asset value and requires new disclosures for Level 3 investments, including a new requirement to disclose changes in unrealized gains or losses recorded in OCI related to Level 3 fair value measurements. ASU 2018-13 is effective for the Company beginning on January 1, 2020, and permits entities to adopt all or certain elements of the new guidance prior to its effective date. ASU 2018-13 requires retrospective application, except for the new disclosures related to Level 3 investments which are to be applied prospectively. As discussed in Note 9 of the Notes to the Consolidated Financial Statements in the 2018 Annual Reports on Form 10-K and in Note 7, PNM and TNMP have investment securities in trusts for decommissioning, reclamation, pension benefits, and other postretirement benefits, which are measured at fair value. Certain investments in these trusts are measured at net asset value per share. These trusts also hold Level 3 investments. The Company is evaluating the requirements of ASU 2018-13, but does not anticipate it will have a significant impact on the Company’s fair value disclosures. Accounting Standards Update 2018-14 – Compensation - Retirement Benefits - Defined Benefit Plans (Topic 715) Disclosure Framework: Changes to the Disclosure Requirements for Defined Benefit Plans In August 2018, the FASB issued ASU 2018-14 to improve benefit plan sponsors’ disclosures for defined benefit pension and other post-employment benefit plans. ASU 2018-14 removes the requirement to disclose the amounts in other comprehensive income expected to be recognized as benefit cost over the next fiscal year and the requirement to disclose the impact of a one-percentage-point change in the assumed health care cost trend rate; clarifies the disclosure requirements for plans with assets that are less than their projected benefit, or accumulated benefit obligation; and requires significant gains and losses affecting benefit obligations during the period be disclosed. ASU 2018-14 is effective for the Company on December 31, 2020, although early adoption is permitted, and requires retrospective application. As discussed in Note 11 of the Notes to the Consolidated Financial Statements in the 2018 Annual Reports on Form 10-K and in Note 10, PNM and TNMP maintain qualified defined benefit, other postretirement benefit plans providing medical and dental benefits, and executive retirement programs. The Company is evaluating the requirements of ASU 2018-14 but does not anticipate these changes will have a significant impact on the Company’s defined benefit and other postretirement benefit plan disclosures. Accounting Standards Update 2018-15 – Intangibles - Goodwill and Other - Internal Use Software (Topic 350): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract In August 2018, the FASB issued ASU 2018-15 to align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for implementation costs incurred to develop or obtain internal-use software. Under ASU 2018-15, entities are required to capitalize implementation costs for hosting arrangements if those costs meet the capitalization requirements for internal-use software arrangements. ASU 2018-15 requires entities to present cash flows, capitalized costs, and amortization expense in the same financial statement line items as other costs incurred for such hosting arrangements. ASU 2018-15 is effective for the Company on January 1, 2020, although early adoption is permitted, and allows entities to apply the new requirements retrospectively or prospectively. The Company is in the process of analyzing the impacts of this new standard. Accounting Standards Update 2018-18 - Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606 In November 2018, the FASB issued ASU 2018-18 to clarify transactions between collaborative arrangement participants that should be recognized as revenue under Topic 606. ASU 2018-18 is effective for the Company on January 1, 2020, although early adoption is permitted, and requires retrospective application. The Company has collaborative arrangements related to its interests in SJGS, Four Corners, PVNGS, and Luna. The Company believes its current accounting practices comply with the requirements of ASU 2018-18 but is in the process of analyzing the impacts of the new standard.

Significant Accounting Policies and Responsibility for Financial Statements

Financial Statement Preparation

In the opinion of management, the accompanying unaudited interim Condensed Consolidated Financial Statements reflect all normal and recurring accruals and adjustments that are necessary to present fairly the consolidated financial position at March 31, 2019 and December 31, 2018, and the consolidated results of operations, comprehensive income, and cash flows for the three months ended March 31, 2019 and 2018. The preparation of financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities, disclosure of contingent assets and liabilities at the date of the financial statements, and the reported amounts of revenues and expenses during the reporting period. Actual results could ultimately differ from those estimated. Weather causes the Company’s results of operations to be seasonal in nature and the results of operations presented in the accompanying Condensed Consolidated Financial Statements are not necessarily representative of operations for an entire year.

The Notes to Condensed Consolidated Financial Statements include disclosures for PNMR, PNM, and TNMP. This report uses the term “Company” when discussing matters of common applicability to PNMR, PNM, and TNMP. Discussions regarding only PNMR, PNM, or TNMP are so indicated. Certain amounts in the 2018 Condensed Consolidated Financial Statements and Notes thereto have been reclassified to conform to the 2019 financial statement presentation.

These Condensed Consolidated Financial Statements are unaudited. Certain information and note disclosures normally included in the annual audited Consolidated Financial Statements have been condensed or omitted, as permitted under the applicable rules and regulations. Readers of these financial statements should refer to PNMR’s, PNM’s, and TNMP’s audited Consolidated Financial Statements and Notes thereto that are included in their respective 2018 Annual Reports on Form 10-K.

GAAP defines subsequent events as events or transactions that occur after the balance sheet date but before financial statements are issued or are available to be issued. Based on their nature, magnitude, and timing, certain subsequent events may be required to be reflected at the balance sheet date and/or required to be disclosed in the financial statements. The Company has evaluated subsequent events as required by GAAP.

Principles of Consolidation

The Condensed Consolidated Financial Statements of each of PNMR, PNM, and TNMP include their accounts and those of subsidiaries in which that entity owns a majority voting interest. PNM also consolidates Valencia (Note 6). PNM owns undivided interests in several jointly-owned power plants and records its pro-rata share of the assets, liabilities, and expenses for those plants. The agreements for the jointly-owned plants provide that if an owner were to default on its payment obligations, the non-defaulting owners would be responsible for their proportionate share of the obligations of the defaulting owner. In exchange, the non-defaulting owners would be entitled to their proportionate share of the generating capacity of the defaulting owner. There have been no such payment defaults under any of the agreements for the jointly-owned plants.

PNMR shared services’ expenses, which represent costs that are primarily driven by corporate level activities, are charged to the business segments. These services are billed at cost and are reflected as general and administrative expenses in the business segments. Other significant intercompany transactions between PNMR, PNM, and TNMP include interest and income tax sharing payments, equity transactions, and interconnection billings (Note 15). All intercompany transactions and balances have been eliminated.

Dividends on Common Stock

Dividends on PNMR’s common stock are declared by the Board. The timing of the declaration of dividends is dependent on the timing of meetings and other actions of the Board.

TNMP declared and paid cash dividends on common stock to PNMR of $10.7 million and $1.0 million in the three months ended March 31, 2019 and 2018.

Investment in NM Renewable Development, LLC

As discussed in Note 1 of the 2018 Annual Reports on Form 10-K, PNMR Development and AEP OnSite Partners created NMRD in September 2017 to pursue the acquisition, development, and ownership of renewable energy generation projects, primarily in the state of New Mexico. NMRD’s current renewable energy capacity in operation is 33.9 MW. PNMR Development and AEP OnSite Partners each have a 50% ownership interest in NMRD. The investment in NMRD is accounted for using the equity method of accounting because PNMR’s ownership interest results in significant influence, but not control, over NMRD and its operations.

In the three months ended March 31, 2019 and 2018, PNMR Development made cash contributions of $7.0 million and $5.0 million to NMRD to be used primarily for its construction activities. For the three months ended March 31, 2019 and 2018, NMRD had revenues of $0.7 million and $0.4 million and net earnings (losses) of $(0.1) million and $0.1 million. At March 31, 2019 and December 31, 2018, NMRD had $8.0 million and $2.6 million of current assets, $65.2 million and $50.8 million of property, plant, and equipment and other assets, $6.1 million and $0.2 million of current liabilities, and $67.1 million and $53.2 million of owners’ equity.

New Accounting Pronouncements

Information concerning recently issued accounting pronouncements that have not been adopted by the Company is presented below. The Company does not expect difficulty in adopting these standards by their required effective dates.

Accounting Standards Update 2016-13 – Financial Instruments – Credit Losses (Topic 326): Measurement of Credit Losses on Financial Instruments

In June 2016, the FASB issued ASU 2016-13, which changes the way entities recognize impairment of many financial assets, including accounts receivable and investments in certain debt securities, by requiring immediate recognition of estimated credit losses expected to occur over the remaining lives of the assets. In November 2018, the FASB clarified that receivables arising from operating leases are not within the scope of Topic 326 for assets measured at amortized costs. Instead, impairments of receivables arising from operating leases should be accounted for in accordance with Topic 842. The Company anticipates adopting ASU 2016-13 as of January 1, 2020, its required effective date. The Company is in the process of analyzing the impacts of this new standard, but does not anticipate it will have a significant impact on its financial statements.

Accounting Standards Update 2017-04 – Intangibles – Goodwill and Other (Topic 350): Simplifying the Test for Goodwill Impairment

In January 2017, the FASB issued ASU 2017-04 to simplify the annual goodwill impairment assessment process. Currently, the first step of a quantitative impairment test requires an entity to compare the fair value of each reporting unit containing goodwill with its carrying value (including goodwill). If as a result of this analysis, the entity concludes there is an indication of impairment in a reporting unit having goodwill, the entity is required to perform the second step of the impairment analysis, determining the amount of goodwill impairment to be recorded. The amount is calculated by comparing the implied fair value of the goodwill to its carrying amount. This exercise requires the entity to allocate the fair value determined in step one to the individual assets and liabilities of the reporting unit. Any remaining fair value would be the implied fair value of goodwill on the testing date. To the extent the recorded amount of goodwill of a reporting unit exceeds the implied fair value determined in step two, an impairment loss would be reflected in results of operations. ASU 2017-04 eliminates the second step of the impairment analysis. Accordingly, if the first step of a quantitative goodwill impairment analysis performed after adoption of ASU 2017-04 indicates that the fair value of a reporting unit is less than its carrying value, the goodwill of that reporting unit would be impaired to the extent of that difference. The Company anticipates it will adopt ASU 2017-04 for impairment testing after January 1, 2020, its required effective date, although early adoption is permitted. However, if there is an indication of potential impairment of goodwill as a result of an impairment assessment prior to 2020, the Company will evaluate the impact of ASU 2017-04 and could elect to early adopt this standard.

Accounting Standards Update 2018-13 – Fair Value Measurements (Topic 820) Disclosure Framework: Changes to the Disclosure Requirements for Fair Value Measurements

In August 2018, the FASB issued ASU 2018-13 to improve fair value disclosures. ASU 2018-13 eliminates certain disclosure requirements related to transfers between Levels 1 and 2 of the fair value hierarchy and the requirement to disclose the valuation process for Level 3 fair value measurements. ASU 2018-13 also amends certain disclosure requirements for investments measured at net asset value and requires new disclosures for Level 3 investments, including a new requirement to disclose changes in unrealized gains or losses recorded in OCI related to Level 3 fair value measurements. ASU 2018-13 is effective for the Company beginning on January 1, 2020, and permits entities to adopt all or certain elements of the new guidance prior to its effective date. ASU 2018-13 requires retrospective application, except for the new disclosures related to Level 3 investments which are to be applied prospectively. As discussed in Note 9 of the Notes to the Consolidated Financial Statements in the 2018 Annual Reports on Form 10-K and in Note 7, PNM and TNMP have investment securities in trusts for decommissioning, reclamation, pension benefits, and other postretirement benefits, which are measured at fair value. Certain investments in these trusts are measured at net asset value per share. These trusts also hold Level 3 investments. The Company is evaluating the requirements of ASU 2018-13, but does not anticipate it will have a significant impact on the Company’s fair value disclosures.

Accounting Standards Update 2018-14 – Compensation - Retirement Benefits - Defined Benefit Plans (Topic 715) Disclosure Framework: Changes to the Disclosure Requirements for Defined Benefit Plans

In August 2018, the FASB issued ASU 2018-14 to improve benefit plan sponsors’ disclosures for defined benefit pension and other post-employment benefit plans. ASU 2018-14 removes the requirement to disclose the amounts in other comprehensive income expected to be recognized as benefit cost over the next fiscal year and the requirement to disclose the impact of a one-percentage-point change in the assumed health care cost trend rate; clarifies the disclosure requirements for plans with assets that are less than their projected benefit, or accumulated benefit obligation; and requires significant gains and losses affecting benefit obligations during the period be disclosed. ASU 2018-14 is effective for the Company on December 31, 2020, although early adoption is permitted, and requires retrospective application. As discussed in Note 11 of the Notes to the Consolidated Financial Statements in the 2018 Annual Reports on Form 10-K and in Note 10, PNM and TNMP maintain qualified defined benefit, other postretirement benefit plans providing medical and dental benefits, and executive retirement programs. The Company is evaluating the requirements of ASU 2018-14 but does not anticipate these changes will have a significant impact on the Company’s defined benefit and other postretirement benefit plan disclosures.

Accounting Standards Update 2018-15 – Intangibles - Goodwill and Other - Internal Use Software (Topic 350): Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That is a Service Contract

In August 2018, the FASB issued ASU 2018-15 to align the requirements for capitalizing implementation costs incurred in a hosting arrangement that is a service contract with the requirements for implementation costs incurred to develop or obtain internal-use software. Under ASU 2018-15, entities are required to capitalize implementation costs for hosting arrangements if those costs meet the capitalization requirements for internal-use software arrangements. ASU 2018-15 requires entities to present cash flows, capitalized costs, and amortization expense in the same financial statement line items as other costs incurred for such hosting arrangements. ASU 2018-15 is effective for the Company on January 1, 2020, although early adoption is permitted, and allows entities to apply the new requirements retrospectively or prospectively. The Company is in the process of analyzing the impacts of this new standard.

Accounting Standards Update 2018-18 - Collaborative Arrangements (Topic 808): Clarifying the Interaction between Topic 808 and Topic 606

In November 2018, the FASB issued ASU 2018-18 to clarify transactions between collaborative arrangement participants that should be recognized as revenue under Topic 606. ASU 2018-18 is effective for the Company on January 1, 2020, although early adoption is permitted, and requires retrospective application. The Company has collaborative arrangements related to its interests in SJGS, Four Corners, PVNGS, and Luna. The Company believes its current accounting practices comply with the requirements of ASU 2018-18 but is in the process of analyzing the impacts of the new standard.