SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)	3 Months Ended
Mar. 31, 2020
Accounting Policies [Abstract]
Basis of Presentation	Basis of Presentation Eversource Energy is a public utility holding company primarily engaged, through its wholly-owned regulated utility subsidiaries, in the energy delivery business. Eversource Energy's wholly-owned regulated utility subsidiaries consist of CL&P, NSTAR Electric and PSNH (electric utilities), Yankee Gas and NSTAR Gas (natural gas utilities) and Aquarion (water utilities). Eversource provides energy delivery and/or water service to approximately four million electric, natural gas and water customers through eight regulated utilities in Connecticut, Massachusetts and New Hampshire. The unaudited condensed consolidated financial statements of Eversource, NSTAR Electric and PSNH include the accounts of each of their respective subsidiaries. Intercompany transactions have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements of Eversource, NSTAR Electric and PSNH and the unaudited condensed financial statements of CL&P are herein collectively referred to as the "financial statements." The combined notes to the financial statements have been prepared pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures included in annual financial statements prepared in accordance with GAAP have been omitted pursuant to such rules and regulations. The accompanying financial statements should be read in conjunction with the Combined Notes to Financial Statements included in Item 8, "Financial Statements and Supplementary Data," of the Eversource 2019 Form 10-K, which was filed with the SEC on February 27, 2020. The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates. The financial statements contain, in the opinion of management, all adjustments (including normal, recurring adjustments) necessary to present fairly Eversource's, CL&P's, NSTAR Electric's and PSNH's financial position as of March 31, 2020 and December 31, 2019, and the results of operations, comprehensive income, common shareholders' equity, and cash flows for the three months ended March 31, 2020 and 2019. The results of operations, comprehensive income, and cash flows for the three months ended March 31, 2020 and 2019 are not necessarily indicative of the results expected for a full year. Eversource consolidates the operations of CYAPC and YAEC, both of which are inactive regional nuclear power companies engaged in the long-term storage of their spent nuclear fuel. Eversource consolidates CYAPC and YAEC because CL&P's, NSTAR Electric's and PSNH's combined ownership and voting interests in each of these entities is greater than 50 percent. Intercompany transactions between CL&P, NSTAR Electric, PSNH and the CYAPC and YAEC companies have been eliminated in consolidation of the Eversource financial statements. Eversource holds several equity ownership interests that are not consolidated and are accounted for under the equity method. Eversource's utility subsidiaries' electric, natural gas and water distribution and transmission businesses are subject to rate-regulation that is based on cost recovery and meets the criteria for application of accounting guidance for entities with rate-regulated operations, which considers the effect of regulation on the differences in the timing of the recognition of certain revenues and expenses from those of other businesses and industries. See Note 2, "Regulatory Accounting," for further information. In March 2020, the World Health Organization declared the outbreak of the 2019 novel coronavirus (COVID-19) a pandemic and President Trump declared a national emergency affecting the entire United States where each state qualifies as being part of a national disaster. The spread of COVID-19 has adversely affected workforces, the overall economy and caused significant volatility in the financial markets. To date, Eversource has not experienced significant operational or financial impacts directly related to the pandemic. Due to the inherent uncertainty of the unprecedented and rapidly evolving situation, management will continue to closely monitor how COVID-19 related developments affect Eversource. As of the date of our filing and based on information available, management is unable to predict the impacts that the COVID-19 pandemic will have on future operations, financial position, results of operations, and cash flows. The extent of the impact in the future will vary and depend in large part on the duration, scope and severity of a national and global economic slowdown, risk of inflation, governmental and regulatory actions, the maintenance of a strong regional and national healthcare system, and the continued spread of the virus, which is mitigated through social distancing measures. Our customer receivable balances and uncollectible accounts have not been materially impacted by COVID-19. We believe that we will be able to develop a successful structure with our respective state regulatory commissions to recover our costs associated with COVID-19, while balancing the impact on our customers’ bills. See Note 1C, "Summary of Significant Accounting Policies - Allowance for Uncollectible Accounts," for further discussion of our evaluation of the allowance for doubtful accounts as of March 31, 2020 in light of the COVID-19 pandemic. An extended economic slowdown could result in lower demand for electricity, natural gas and/or water by our commercial and industrial customers. However, fluctuations in retail sales volumes for CL&P, NSTAR Electric, Yankee Gas, NSTAR Gas and our Connecticut water distribution business are not expected to materially impact earnings due to their respective regulatory commission-approved distribution revenue decoupling mechanisms. The revenue decoupling mechanisms mitigate the impact of lower demand and resulting lost sales revenues by allowing for a true-up to occur as part of each company’s annual decoupling filing. These revenue decoupling mechanisms qualify as alternative revenue programs in accordance with accounting guidance for rate-regulated operations. As of March 31, 2020, we did not have indicators of triggering events for impairments to our goodwill, long-lived assets, available-for-sale debt securities, or equity method investment carrying values. Certain reclassifications of prior period data were made in the accompanying financial statements to conform to the current period presentation. The Eversource and PSNH 2019 statements of cash flows and the 2019 segment footnote were revised to correct an error in the presentation of non-cash capital additions. The impact of this revision on the statement of cash flows is a decrease to operating cash inflows in Accounts Payable of $46.6 million and a corresponding decrease to investing cash outflows in Investments in Property, Plant and Equipment for the quarter ended March 31, 2019. This revision is not deemed material, individually or in the aggregate, to the previously issued financial statements.
Accounting Standards	Accounting Standards Accounting Standards Issued but Not Yet Effective: In December 2019, the FASB issued Accounting Standards Update (ASU) 2019-12, Income Taxes (Topic 740) - Simplifying the Accounting for Income Taxes, which eliminates certain exceptions to the general principles of current income tax guidance in ASC 740 and simplifies and improves consistency in application of that income tax guidance through clarifications of and amendments to ASC 740. The guidance is effective in the first quarter of 2021. The ASU is not expected to have a material impact on the financial statements of Eversource, CL&P, NSTAR Electric and PSNH. Accounting Standards Recently Adopted: On January 1, 2020, the Company adopted ASU 2016-13, Financial Instruments - Credit Losses (Topic 326), which provides a model for recognizing credit losses on financial instruments based on an estimate of current expected losses, requiring immediate recognition of credit losses expected over the life of a financial instrument. The Company determined the impacts of this standard on the allowance for credit losses on its financial instruments, primarily accounts receivable. As of January 1, 2020, the Company recorded increases to the allowance for uncollectible accounts for late fees and other receivable amounts of $1.6 million, $0.9 million, $0.2 million and $0.3 million at Eversource, CL&P, NSTAR Electric and PSNH, respectively. The impact to retained earnings, net of tax, was $1.5 million, $0.9 million, $0.2 million and $0.3 million at Eversource, CL&P, NSTAR Electric and PSNH, respectively. The Company also adjusted the allowance for uncollectible amounts of hardship receivables and other low-income assistance programs, which are ultimately collectible in rates at specified points in time under approved regulatory mechanisms. The impact on the allowance, which was offset in other long-term assets on the balance sheets, was an increase of $22.2 million and $21.3 million at Eversource and CL&P, respectively, and a decrease of $1.5 million at NSTAR Electric. See Note 1C, “Summary of Significant Accounting Policies - Allowance for Uncollectible Accounts,” for further information. The Company adopted ASU 2017-04, Intangibles - Goodwill and Other (Topic 350), Simplifying the Test for Goodwill Impairment as of January 1, 2020. The ASU simplified the accounting for goodwill impairment by removing a complex step in the goodwill impairment test. Under the guidance, goodwill impairment is measured as the amount by which its carrying value exceeds its fair value. The ASU is not expected to have an impact on the financial statements of Eversource. On January 1, 2020, the Company adopted ASU 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40) - Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The ASU aligned the requirements for capitalizing costs incurred to implement a cloud computing arrangement with existing internal-use software guidance. The prospective implementation of this standard did not have any impact on the financial statements of Eversource, CL&P, NSTAR Electric or PSNH for the period ending March 31, 2020. On January 1, 2020, the Company prospectively adopted ASU 2018-13, Fair Value Measurement (Topic 820), Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement. The ASU modified fair value disclosure requirements. The standard includes new disclosure requirements for Level 3 unobservable inputs and eliminated the requirement to disclose certain information relating to transfers between levels. The modified disclosures are included in Note 1D, “Summary of Significant Accounting Policies - Fair Value Measurements,” and Note 4, “Derivative Instruments.”
Allowance for Uncollectible Accounts	Allowance for Uncollectible Accounts Receivables, Net on the balance sheets primarily includes trade receivables from retail customers and customers related to wholesale transmission contracts, wholesale market sales, sales of RECs and property rentals. Receivables, Net also includes customer receivables for the purchase of electricity from a competitive third party supplier, the current portion of customer energy efficiency loans, property damage receivables and other miscellaneous receivables. There is no material concentration of receivables. Receivables are recorded at amortized cost, net of a credit loss provision (or allowance for uncollectible accounts). Receivables are presented net of expected credit losses at estimated net realizable value by maintaining an allowance for uncollectible accounts. Effective January 1, 2020, the current expected credit loss (CECL) model was applied to receivables for purposes of calculating the allowance for uncollectible accounts. This model is based on expected losses and results in the recognition of estimated expected credit losses, including uncollectible amounts for both billed and unbilled revenues, over the life of the receivable at the time a receivable is recorded. The allowance for uncollectible accounts is determined based upon a variety of judgments and factors, including the application of an estimated uncollectible percentage to each receivable aging category. Factors in determining credit loss include historical collection, write-off experience, and management's assessment of collectibility from customers, including current conditions, reasonable forecasts, and expectations of future collectibility and collection efforts. Management continuously assesses the collectibility of receivables and adjusts estimates based on actual experience and future expectations based on economic indicators. Management also monitors the aging analysis of receivables to determine if there are changes in the collections of accounts receivable. Receivable balances are written off against the allowance for uncollectible accounts when the customer accounts are no longer in service and these balances are deemed to be uncollectible. As of March 31, 2020, management evaluated the adequacy of the allowance for uncollectible accounts in light of the COVID-19 pandemic and the economic downturn to date. This evaluation included an analysis of collection and customer payment trends in 2020, economic conditions, flexible payment plans and financial hardship arrearage management programs being offered to customers, and the impacts of federal governmental pandemic relief programs for our customers and the expansion of unemployment benefits initiatives, which help to mitigate the potential for increasing customer account delinquencies. Additionally, management considered past economic declines and corresponding uncollectible reserves as part of the current assessment. Based upon the evaluation performed, management concluded that the reserve balance as of March 31, 2020 adequately reflected the collection risk and net realizable value for Eversource’s receivables. Management will continue to evaluate the adequacy of the uncollectible allowance in future reporting periods based on an ongoing assessment of accounts receivable collections, delinquency statistics, and analysis of aging-based quantitative assessments. The PURA allows CL&P and Yankee Gas to accelerate the recovery of accounts receivable balances attributable to qualified customers under financial or medical duress (uncollectible hardship accounts receivable) outstanding for greater than 180 days and 90 days, respectively. The DPU allows NSTAR Electric and NSTAR Gas to recover in rates amounts associated with certain uncollectible hardship accounts receivable. These uncollectible hardship customer account balances are included in Regulatory Assets or Other Long-Term Assets on the balance sheets. Hardship customers are protected from shut-off in certain circumstances, and historical collection experience has reflected a higher default risk as compared to the rest of the receivable population. As a result of the adoption of ASU 2016-13, management aligned the allowance for uncollectible hardship accounts across all regulatory jurisdictions, using a higher credit risk profile for this pool of trade receivables as compared to non-hardship receivables. Implementation impacts of the accounting standard on the allowance for uncollectible hardship accounts are reflected in the rollforward of the uncollectible allowance in the table below. The allowance for uncollectible hardship accounts is included in the total uncollectible allowance balance. The total allowance for uncollectible accounts is included in Receivables, Net on the balance sheets.
Fair Value Measurements	Fair Value Measurements Fair value measurement guidance is applied to derivative contracts that are not elected or designated as "normal purchases" or "normal sales" (normal) and to the marketable securities held in trusts. Fair value measurement guidance is also applied to valuations of the investments used to calculate the funded status of pension and PBOP plans, the nonrecurring fair value measurements of nonfinancial assets such as goodwill, long-lived assets and AROs, and the estimated fair value of preferred stock, long-term debt and RRBs. Fair Value Hierarchy: In measuring fair value, Eversource uses observable market data when available in order to minimize the use of unobservable inputs. Inputs used in fair value measurements are categorized into three fair value hierarchy levels for disclosure purposes. The entire fair value measurement is categorized based on the lowest level of input that is significant to the fair value measurement. Eversource evaluates the classification of assets and liabilities measured at fair value on a quarterly basis. The three levels of the fair value hierarchy are described below: Level 1 - Inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities as of the reporting date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis. Level 2 - Inputs are quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-derived valuations in which all significant inputs are observable. Level 3 - Quoted market prices are not available. Fair value is derived from valuation techniques in which one or more significant inputs or assumptions are unobservable. Where possible, valuation techniques incorporate observable market inputs that can be validated to external sources such as industry exchanges, including prices of energy and energy-related products. Uncategorized - Investments that are measured at net asset value are not categorized within the fair value hierarchy.
Other Taxes	Other TaxesEversource's companies that serve customers in Connecticut collect gross receipts taxes levied by the state of Connecticut from their customers. Separate from above were amounts recorded as Taxes Other Than Income Taxes at CL&P related to the remittance to the State of Connecticut of energy efficiency funds collected from customers of $10.7 million for the three months ended March 31, 2019. Energy efficiency funds collected from customers after July 1, 2019 are no longer subject to remittance to the State of Connecticut. These amounts were recorded separately, with collections in Operating Revenues and with payments in Taxes Other Than Income Taxes on the Eversource and CL&P statements of income. As agents for state and local governments, Eversource's companies that serve customers in Connecticut and Massachusetts collect certain sales taxes that are recorded on a net basis with no impact on the statements of income.
Earnings Per Share	Basic EPS is computed based upon the weighted average number of common shares outstanding during each period. Diluted EPS is computed on the basis of the weighted average number of common shares outstanding plus the potential dilutive effect of certain share-based compensation awards and the equity forward sale agreement, as if they were converted into outstanding common shares. The dilutive effect of unvested RSU and performance share awards, as well as the equity forward sale agreement, is calculated using the treasury stock method. RSU and performance share awards are included in basic weighted average common shares outstanding as of the date that all necessary vesting conditions have been satisfied. As described in Note 12, "Common Shares," earnings per share dilution, if any, related to the forward sale agreement is determined under the treasury stock method until settlement of the forward sale agreement. Under this method, the number of Eversource common shares used in calculating diluted EPS is deemed to be increased by the excess, if any, of the number of shares that would be issued upon physical settlement of the forward sale agreement less the number of shares that would be purchased by Eversource in the market (based on the average market price during the same reporting period) using the proceeds receivable upon settlement (based on the adjusted forward sale price at the end of that reporting period). Share dilution occurs when the average market price of Eversource's common shares is higher than the adjusted forward sale price.
Restricted Cash	Special Deposits represent cash collections related to the PSNH RRB customer charges that are held in trust, required ISO-NE cash deposits, and CYAPC and YAEC cash balances. Special Deposits are included in Current Assets on the balance sheets. Restricted cash included in Marketable Securities represents money market funds held in trusts to fund certain non-qualified executive benefits and restricted trusts to fund CYAPC and YAEC's spent nuclear fuel storage obligations.

SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (Policies)

3 Months Ended

Mar. 31, 2020

Eversource Energy is a public utility holding company primarily engaged, through its wholly-owned regulated utility subsidiaries, in the energy delivery business. Eversource Energy's wholly-owned regulated utility subsidiaries consist of CL&P, NSTAR Electric and PSNH (electric utilities), Yankee Gas and NSTAR Gas (natural gas utilities) and Aquarion (water utilities). Eversource provides energy delivery and/or water service to approximately four million electric, natural gas and water customers through eight regulated utilities in Connecticut, Massachusetts and New Hampshire.

The unaudited condensed consolidated financial statements of Eversource, NSTAR Electric and PSNH include the accounts of each of their respective subsidiaries. Intercompany transactions have been eliminated in consolidation. The accompanying unaudited condensed consolidated financial statements of Eversource, NSTAR Electric and PSNH and the unaudited condensed financial statements of CL&P are herein collectively referred to as the "financial statements."

The combined notes to the financial statements have been prepared pursuant to the rules and regulations of the SEC. Certain information and footnote disclosures included in annual financial statements prepared in accordance with GAAP have been omitted pursuant to such rules and regulations. The accompanying financial statements should be read in conjunction with the Combined Notes to Financial Statements included in Item 8, "Financial Statements and Supplementary Data," of the Eversource 2019 Form 10-K, which was filed with the SEC on February 27, 2020. The preparation of the financial statements in conformity with GAAP requires management to make estimates and assumptions that affect the reported amounts of assets and liabilities and the disclosure of contingent liabilities as of the date of the financial statements and the reported amounts of revenues and expenses during the reporting period. Actual results could differ from those estimates.

The financial statements contain, in the opinion of management, all adjustments (including normal, recurring adjustments) necessary to present fairly Eversource's, CL&P's, NSTAR Electric's and PSNH's financial position as of March 31, 2020 and December 31, 2019, and the results of operations, comprehensive income, common shareholders' equity, and cash flows for the three months ended March 31, 2020 and 2019. The results of operations, comprehensive income, and cash flows for the three months ended March 31, 2020 and 2019 are not necessarily indicative of the results expected for a full year.

Eversource consolidates the operations of CYAPC and YAEC, both of which are inactive regional nuclear power companies engaged in the long-term storage of their spent nuclear fuel. Eversource consolidates CYAPC and YAEC because CL&P's, NSTAR Electric's and PSNH's combined ownership and voting interests in each of these entities is greater than 50 percent. Intercompany transactions between CL&P, NSTAR Electric, PSNH and the CYAPC and YAEC companies have been eliminated in consolidation of the Eversource financial statements.

Eversource holds several equity ownership interests that are not consolidated and are accounted for under the equity method.

Eversource's utility subsidiaries' electric, natural gas and water distribution and transmission businesses are subject to rate-regulation that is based on cost recovery and meets the criteria for application of accounting guidance for entities with rate-regulated operations, which considers the effect of regulation on the differences in the timing of the recognition of certain revenues and expenses from those of other businesses and industries. See Note 2, "Regulatory Accounting," for further information.

In March 2020, the World Health Organization declared the outbreak of the 2019 novel coronavirus (COVID-19) a pandemic and President Trump declared a national emergency affecting the entire United States where each state qualifies as being part of a national disaster. The spread of COVID-19 has adversely affected workforces, the overall economy and caused significant volatility in the financial markets. To date, Eversource has not experienced significant operational or financial impacts directly related to the pandemic. Due to the inherent uncertainty of the unprecedented and rapidly evolving situation, management will continue to closely monitor how COVID-19 related developments affect Eversource. As of the date of our filing and based on information available, management is unable to predict the impacts that the COVID-19 pandemic will have on future operations, financial position, results of operations, and cash flows. The extent of the impact in the future will vary and depend in large part on the duration, scope and severity of a national and global economic slowdown, risk of inflation, governmental and regulatory actions, the maintenance of a strong regional and national healthcare system, and the continued spread of the virus, which is mitigated through social distancing measures.

Our customer receivable balances and uncollectible accounts have not been materially impacted by COVID-19. We believe that we will be able to develop a successful structure with our respective state regulatory commissions to recover our costs associated with COVID-19, while balancing the impact on our customers’ bills. See Note 1C, "Summary of Significant Accounting Policies - Allowance for Uncollectible Accounts," for further discussion of our evaluation of the allowance for doubtful accounts as of March 31, 2020 in light of the COVID-19 pandemic.

An extended economic slowdown could result in lower demand for electricity, natural gas and/or water by our commercial and industrial customers. However, fluctuations in retail sales volumes for CL&P, NSTAR Electric, Yankee Gas, NSTAR Gas and our Connecticut water distribution business are not expected to materially impact earnings due to their respective regulatory commission-approved distribution revenue decoupling mechanisms. The revenue decoupling mechanisms mitigate the impact of lower demand and resulting lost sales revenues by allowing for a true-up to occur as part of each company’s annual decoupling filing. These revenue decoupling mechanisms qualify as alternative revenue programs in accordance with accounting guidance for rate-regulated operations.

As of March 31, 2020, we did not have indicators of triggering events for impairments to our goodwill, long-lived assets, available-for-sale debt securities, or equity method investment carrying values.

Certain reclassifications of prior period data were made in the accompanying financial statements to conform to the current period presentation.

The Eversource and PSNH 2019 statements of cash flows and the 2019 segment footnote were revised to correct an error in the presentation of non-cash capital additions. The impact of this revision on the statement of cash flows is a decrease to operating cash inflows in Accounts Payable of $46.6 million and a corresponding decrease to investing cash outflows in Investments in Property, Plant and Equipment for the quarter ended March 31, 2019. This revision is not deemed material, individually or in the aggregate, to the previously issued financial statements.

Accounting Standards

Accounting Standards Issued but Not Yet Effective: In December 2019, the FASB issued Accounting Standards Update (ASU) 2019-12, Income Taxes (Topic 740) - Simplifying the Accounting for Income Taxes, which eliminates certain exceptions to the general principles of current income tax guidance in ASC 740 and simplifies and improves consistency in application of that income tax guidance through clarifications of and amendments to ASC 740. The guidance is effective in the first quarter of 2021. The ASU is not expected to have a material impact on the financial statements of Eversource, CL&P, NSTAR Electric and PSNH.

Accounting Standards Recently Adopted: On January 1, 2020, the Company adopted ASU 2016-13, Financial Instruments - Credit Losses (Topic 326), which provides a model for recognizing credit losses on financial instruments based on an estimate of current expected losses, requiring immediate recognition of credit losses expected over the life of a financial instrument. The Company determined the impacts of this standard on the allowance for credit losses on its financial instruments, primarily accounts receivable. As of January 1, 2020, the Company recorded increases to the allowance for uncollectible accounts for late fees and other receivable amounts of $1.6 million, $0.9 million, $0.2 million and $0.3 million at Eversource, CL&P, NSTAR Electric and PSNH, respectively. The impact to retained earnings, net of tax, was $1.5 million, $0.9 million, $0.2 million and $0.3 million at Eversource, CL&P, NSTAR Electric and PSNH, respectively.

The Company also adjusted the allowance for uncollectible amounts of hardship receivables and other low-income assistance programs, which are ultimately collectible in rates at specified points in time under approved regulatory mechanisms. The impact on the allowance, which was offset in other long-term assets on the balance sheets, was an increase of $22.2 million and $21.3 million at Eversource and CL&P, respectively, and a decrease of $1.5 million at NSTAR Electric. See Note 1C, “Summary of Significant Accounting Policies - Allowance for Uncollectible Accounts,” for further information.

The Company adopted ASU 2017-04, Intangibles - Goodwill and Other (Topic 350), Simplifying the Test for Goodwill Impairment as of January 1, 2020. The ASU simplified the accounting for goodwill impairment by removing a complex step in the goodwill impairment test. Under the guidance, goodwill impairment is measured as the amount by which its carrying value exceeds its fair value. The ASU is not expected to have an impact on the financial statements of Eversource.

On January 1, 2020, the Company adopted ASU 2018-15, Intangibles - Goodwill and Other - Internal-Use Software (Subtopic 350-40) - Customer’s Accounting for Implementation Costs Incurred in a Cloud Computing Arrangement That Is a Service Contract. The ASU aligned the requirements for capitalizing costs incurred to implement a cloud computing arrangement with existing internal-use software guidance. The prospective implementation of this standard did not have any impact on the financial statements of Eversource, CL&P, NSTAR Electric or PSNH for the period ending March 31, 2020.

On January 1, 2020, the Company prospectively adopted ASU 2018-13, Fair Value Measurement (Topic 820), Disclosure Framework - Changes to the Disclosure Requirements for Fair Value Measurement. The ASU modified fair value disclosure requirements. The standard includes new disclosure requirements for Level 3 unobservable inputs and eliminated the requirement to disclose certain information relating to transfers between levels. The modified disclosures are included in Note 1D, “Summary of Significant Accounting Policies - Fair Value Measurements,” and Note 4, “Derivative Instruments.”

Allowance for Uncollectible Accounts

Receivables, Net on the balance sheets primarily includes trade receivables from retail customers and customers related to wholesale transmission contracts, wholesale market sales, sales of RECs and property rentals. Receivables, Net also includes customer receivables for the purchase of electricity from a competitive third party supplier, the current portion of customer energy efficiency loans, property damage receivables and other miscellaneous receivables. There is no material concentration of receivables. Receivables are recorded at amortized cost, net of a credit loss provision (or allowance for uncollectible accounts).

Receivables are presented net of expected credit losses at estimated net realizable value by maintaining an allowance for uncollectible accounts. Effective January 1, 2020, the current expected credit loss (CECL) model was applied to receivables for purposes of calculating the allowance for uncollectible accounts. This model is based on expected losses and results in the recognition of estimated expected credit losses, including uncollectible amounts for both billed and unbilled revenues, over the life of the receivable at the time a receivable is recorded.

The allowance for uncollectible accounts is determined based upon a variety of judgments and factors, including the application of an estimated uncollectible percentage to each receivable aging category. Factors in determining credit loss include historical collection, write-off experience, and management's assessment of collectibility from customers, including current conditions, reasonable forecasts, and expectations of future collectibility and collection efforts. Management continuously assesses the collectibility of receivables and adjusts estimates based on actual experience and future expectations based on economic indicators. Management also monitors the aging analysis of receivables to determine if there are changes in the collections of accounts receivable. Receivable balances are written off against the allowance for uncollectible accounts when the customer accounts are no longer in service and these balances are deemed to be uncollectible.

As of March 31, 2020, management evaluated the adequacy of the allowance for uncollectible accounts in light of the COVID-19 pandemic and the economic downturn to date. This evaluation included an analysis of collection and customer payment trends in 2020, economic conditions, flexible payment plans and financial hardship arrearage management programs being offered to customers, and the impacts of federal governmental pandemic relief programs for our customers and the expansion of unemployment benefits initiatives, which help to mitigate the potential for increasing customer account delinquencies. Additionally, management considered past economic declines and corresponding uncollectible reserves as part of the current assessment. Based upon the evaluation performed, management concluded that the reserve balance as of March 31, 2020 adequately reflected the collection risk and net realizable value for Eversource’s receivables. Management will continue to evaluate the adequacy of the uncollectible allowance in future reporting periods based on an ongoing assessment of accounts receivable collections, delinquency statistics, and analysis of aging-based quantitative assessments.

The PURA allows CL&P and Yankee Gas to accelerate the recovery of accounts receivable balances attributable to qualified customers under financial or medical duress (uncollectible hardship accounts receivable) outstanding for greater than 180 days and 90 days, respectively. The DPU allows NSTAR Electric and NSTAR Gas to recover in rates amounts associated with certain uncollectible hardship accounts receivable. These uncollectible hardship customer account balances are included in Regulatory Assets or Other Long-Term Assets on the balance sheets. Hardship customers are protected from shut-off in certain circumstances, and historical collection experience has reflected a higher default risk as compared to the rest of the receivable population. As a result of the adoption of ASU 2016-13, management aligned the allowance for uncollectible hardship accounts across all regulatory jurisdictions, using a higher credit risk profile for this pool of trade receivables as compared to non-hardship receivables. Implementation impacts of the accounting standard on the allowance for uncollectible hardship accounts are reflected in the rollforward of the uncollectible allowance in the table below. The allowance for uncollectible hardship accounts is included in the total uncollectible allowance balance.

The total allowance for uncollectible accounts is included in Receivables, Net on the balance sheets.

Fair Value Measurements

Fair value measurement guidance is applied to derivative contracts that are not elected or designated as "normal purchases" or "normal sales" (normal) and to the marketable securities held in trusts. Fair value measurement guidance is also applied to valuations of the investments used to calculate the funded status of pension and PBOP plans, the nonrecurring fair value measurements of nonfinancial assets such as goodwill, long-lived assets and AROs, and the estimated fair value of preferred stock, long-term debt and RRBs.

Fair Value Hierarchy: In measuring fair value, Eversource uses observable market data when available in order to minimize the use of unobservable inputs. Inputs used in fair value measurements are categorized into three fair value hierarchy levels for disclosure purposes. The entire fair value measurement is categorized based on the lowest level of input that is significant to the fair value measurement. Eversource evaluates the classification of assets and liabilities measured at fair value on a quarterly basis. The three levels of the fair value hierarchy are described below:

Level 1 - Inputs are quoted prices (unadjusted) in active markets for identical assets or liabilities as of the reporting date. Active markets are those in which transactions for the asset or liability occur in sufficient frequency and volume to provide pricing information on an ongoing basis.

Level 2 - Inputs are quoted prices for similar instruments in active markets, quoted prices for identical or similar instruments in markets that are not active, and model-derived valuations in which all significant inputs are observable.

Level 3 - Quoted market prices are not available. Fair value is derived from valuation techniques in which one or more significant inputs or assumptions are unobservable. Where possible, valuation techniques incorporate observable market inputs that can be validated to external sources such as industry exchanges, including prices of energy and energy-related products.

Uncategorized - Investments that are measured at net asset value are not categorized within the fair value hierarchy.

Other Taxes

Other TaxesEversource's companies that serve customers in Connecticut collect gross receipts taxes levied by the state of Connecticut from their customers.

Separate from above were amounts recorded as Taxes Other Than Income Taxes at CL&P related to the remittance to the State of Connecticut of energy efficiency funds collected from customers of $10.7 million for the three months ended March 31, 2019. Energy efficiency funds collected from customers after July 1, 2019 are no longer subject to remittance to the State of Connecticut. These amounts were recorded separately, with collections in Operating Revenues and with payments in Taxes Other Than Income Taxes on the Eversource and CL&P statements of income.

As agents for state and local governments, Eversource's companies that serve customers in Connecticut and Massachusetts collect certain sales taxes that are recorded on a net basis with no impact on the statements of income.

Earnings Per Share

Basic EPS is computed based upon the weighted average number of common shares outstanding during each period. Diluted EPS is computed on the basis of the weighted average number of common shares outstanding plus the potential dilutive effect of certain share-based compensation awards and the equity forward sale agreement, as if they were converted into outstanding common shares. The dilutive effect of unvested RSU and performance share awards, as well as the equity forward sale agreement, is calculated using the treasury stock method. RSU and performance share awards are included in basic weighted average common shares outstanding as of the date that all necessary vesting conditions have been satisfied.

As described in Note 12, "Common Shares," earnings per share dilution, if any, related to the forward sale agreement is determined under the treasury stock method until settlement of the forward sale agreement. Under this method, the number of Eversource common shares used in calculating diluted EPS is deemed to be increased by the excess, if any, of the number of shares that would be issued upon physical settlement of the forward sale agreement less the number of shares that would be purchased by Eversource in the market (based on the average market price during the same reporting period) using the proceeds receivable upon settlement (based on the adjusted forward sale price at the end of that reporting period). Share dilution occurs when the average market price of Eversource's common shares is higher than the adjusted forward sale price.

Restricted Cash

Special Deposits represent cash collections related to the PSNH RRB customer charges that are held in trust, required ISO-NE cash deposits, and CYAPC and YAEC cash balances. Special Deposits are included in Current Assets on the balance sheets. Restricted cash included in Marketable Securities represents money market funds held in trusts to fund certain non-qualified executive benefits and restricted trusts to fund CYAPC and YAEC's spent nuclear fuel storage obligations.