SHORT-TERM DEBT	12 Months Ended
Dec. 31, 2016
Debt Disclosure [Abstract]
SHORT-TERM DEBT	SHORT-TERM DEBT Short-Term Debt Borrowing Limits: The amount of short-term borrowings that may be incurred by CL&P, NSTAR Electric, WMECO and NPT is subject to periodic approval by the FERC. As a result of the NHPUC having jurisdiction over PSNH's short-term debt, PSNH is not currently required to obtain FERC approval for its short-term borrowings. On June 16, 2015, the FERC granted authorization that allows CL&P and WMECO to incur total short-term borrowings up to a maximum of $600 million and $300 million, respectively, through December 31, 2017. On August 8, 2016, the FERC granted authorization to allow NSTAR Electric to issue total short-term debt securities in an aggregate principal amount not to exceed $655 million outstanding at any one time, through October 23, 2018. On November 3, 2016, FERC authorized NPT to issue up to an aggregate of $800 million in short-term debt and long-term debt through December 31, 2018. PSNH is authorized by regulation of the NHPUC to incur short-term borrowings up to 10 percent of net fixed plant plus an additional $60 million until further ordered by the NHPUC. As of December 31, 2016, PSNH's short-term debt authorization under the 10 percent of net fixed plant test plus $60 million totaled approximately $349 million. CL&P's certificate of incorporation contains preferred stock provisions restricting the amount of unsecured debt that CL&P may incur, including limiting unsecured indebtedness with a maturity of less than 10 years to 10 percent of total capitalization. As of December 31, 2016, CL&P had $557.6 million of unsecured debt capacity available under this authorization. Yankee Gas and NSTAR Gas are not required to obtain approval from any state or federal authority to incur short-term debt. Commercial Paper Programs and Credit Agreements: Eversource parent has a $1.45 billion commercial paper program allowing Eversource parent to issue commercial paper as a form of short-term debt. As of December 31, 2016 and 2015, Eversource parent had approximately $1.0 billion and approximately $1.1 billion, respectively, in short-term borrowings outstanding under the Eversource parent commercial paper program, leaving $428.0 million and $351.5 million of available borrowing capacity as of December 31, 2016 and 2015, respectively. The weighted-average interest rate on these borrowings as of December 31, 2016 and 2015 was 0.88 percent and 0.72 percent, respectively. As of December 31, 2016, there were intercompany loans from Eversource parent of $80.1 million to CL&P, $160.9 million to PSNH, and $51.0 million to WMECO. As of December 31, 2015, there were intercompany loans from Eversource parent of $277.4 million to CL&P, $231.3 million to PSNH and $143.4 million to WMECO. Eversource parent, CL&P, PSNH, WMECO, NSTAR Gas and Yankee Gas are parties to a five-year $1.45 billion revolving credit facility. Effective September 26, 2016, the revolving credit facility's termination date was extended for one additional year to September 4, 2021. The revolving credit facility serves to backstop Eversource parent's $1.45 billion commercial paper program. There were no borrowings outstanding on the revolving credit facility as of December 31, 2016 or 2015. NSTAR Electric has a $450 million commercial paper program allowing NSTAR Electric to issue commercial paper as a form of short-term debt. As of December 31, 2016 and 2015, NSTAR Electric had $126.5 million and $62.5 million, respectively, in short-term borrowings outstanding under its commercial paper program, leaving $323.5 million and $387.5 million of available borrowing capacity as of December 31, 2016 and 2015, respectively. The weighted-average interest rate on these borrowings as of December 31, 2016 and 2015 was 0.71 percent and 0.40 percent, respectively. NSTAR Electric is a party to a five-year $450 million revolving credit facility. Effective September 26, 2016, the revolving credit facility's termination date was extended for one additional year to September 4, 2021. The revolving credit facility serves to backstop NSTAR Electric's $450 million commercial paper program. There were no borrowings outstanding on the revolving credit facility as of December 31, 2016 or 2015. Amounts outstanding under the commercial paper programs are included in Notes Payable for Eversource and NSTAR Electric and are classified in current liabilities on the balance sheets as all borrowings are outstanding for no more than 364 days at one time. Intercompany loans from Eversource parent to CL&P, PSNH and WMECO are included in Notes Payable to Eversource Parent and are classified in current liabilities on their respective balance sheets. Intercompany loans from Eversource to CL&P, PSNH and WMECO are eliminated in consolidation on Eversource's balance sheets. Under the credit facilities described above, Eversource and its subsidiaries must comply with certain financial and non-financial covenants, including a consolidated debt to total capitalization ratio. As of December 31, 2016 and 2015, Eversource and its subsidiaries were in compliance with these covenants. If Eversource or its subsidiaries were not in compliance with these covenants, an event of default would occur requiring all outstanding borrowings by such borrower to be repaid and additional borrowings by such borrower would not be permitted under its respective credit facility.

SHORT-TERM DEBT

Short-Term Debt Borrowing Limits: The amount of short-term borrowings that may be incurred by CL&P, NSTAR Electric, WMECO and NPT is subject to periodic approval by the FERC. As a result of the NHPUC having jurisdiction over PSNH's short-term debt, PSNH is not currently required to obtain FERC approval for its short-term borrowings. On June 16, 2015, the FERC granted authorization that allows CL&P and WMECO to incur total short-term borrowings up to a maximum of $600 million and $300 million, respectively, through December 31, 2017. On August 8, 2016, the FERC granted authorization to allow NSTAR Electric to issue total short-term debt securities in an aggregate principal amount not to exceed $655 million outstanding at any one time, through October 23, 2018. On November 3, 2016, FERC authorized NPT to issue up to an aggregate of $800 million in short-term debt and long-term debt through December 31, 2018.

PSNH is authorized by regulation of the NHPUC to incur short-term borrowings up to 10 percent of net fixed plant plus an additional $60 million until further ordered by the NHPUC. As of December 31, 2016, PSNH's short-term debt authorization under the 10 percent of net fixed plant test plus $60 million totaled approximately $349 million.

CL&P's certificate of incorporation contains preferred stock provisions restricting the amount of unsecured debt that CL&P may incur, including limiting unsecured indebtedness with a maturity of less than 10 years to 10 percent of total capitalization. As of December 31, 2016, CL&P had $557.6 million of unsecured debt capacity available under this authorization.

Yankee Gas and NSTAR Gas are not required to obtain approval from any state or federal authority to incur short-term debt.

Commercial Paper Programs and Credit Agreements: Eversource parent has a $1.45 billion commercial paper program allowing Eversource parent to issue commercial paper as a form of short-term debt. As of December 31, 2016 and 2015, Eversource parent had approximately $1.0 billion and approximately $1.1 billion, respectively, in short-term borrowings outstanding under the Eversource parent commercial paper program, leaving $428.0 million and $351.5 million of available borrowing capacity as of December 31, 2016 and 2015, respectively. The weighted-average interest rate on these borrowings as of December 31, 2016 and 2015 was 0.88 percent and 0.72 percent, respectively. As of December 31, 2016, there were intercompany loans from Eversource parent of $80.1 million to CL&P, $160.9 million to PSNH, and $51.0 million to WMECO. As of December 31, 2015, there were intercompany loans from Eversource parent of $277.4 million to CL&P, $231.3 million to PSNH and $143.4 million to WMECO. Eversource parent, CL&P, PSNH, WMECO, NSTAR Gas and Yankee Gas are parties to a five-year $1.45 billion revolving credit facility. Effective September 26, 2016, the revolving credit facility's termination date was extended for one additional year to September 4, 2021. The revolving credit facility serves to backstop Eversource parent's $1.45 billion commercial paper program. There were no borrowings outstanding on the revolving credit facility as of December 31, 2016 or 2015.

NSTAR Electric has a $450 million commercial paper program allowing NSTAR Electric to issue commercial paper as a form of short-term debt. As of December 31, 2016 and 2015, NSTAR Electric had $126.5 million and $62.5 million, respectively, in short-term borrowings outstanding under its commercial paper program, leaving $323.5 million and $387.5 million of available borrowing capacity as of December 31, 2016 and 2015, respectively. The weighted-average interest rate on these borrowings as of December 31, 2016 and 2015 was 0.71 percent and 0.40 percent, respectively. NSTAR Electric is a party to a five-year $450 million revolving credit facility. Effective September 26, 2016, the revolving credit facility's termination date was extended for one additional year to September 4, 2021. The revolving credit facility serves to backstop NSTAR Electric's $450 million commercial paper program. There were no borrowings outstanding on the revolving credit facility as of December 31, 2016 or 2015.

Amounts outstanding under the commercial paper programs are included in Notes Payable for Eversource and NSTAR Electric and are classified in current liabilities on the balance sheets as all borrowings are outstanding for no more than 364 days at one time. Intercompany loans from Eversource parent to CL&P, PSNH and WMECO are included in Notes Payable to Eversource Parent and are classified in current liabilities on their respective balance sheets. Intercompany loans from Eversource to CL&P, PSNH and WMECO are eliminated in consolidation on Eversource's balance sheets.

Under the credit facilities described above, Eversource and its subsidiaries must comply with certain financial and non-financial covenants, including a consolidated debt to total capitalization ratio. As of December 31, 2016 and 2015, Eversource and its subsidiaries were in compliance with these covenants. If Eversource or its subsidiaries were not in compliance with these covenants, an event of default would occur requiring all outstanding borrowings by such borrower to be repaid and additional borrowings by such borrower would not be permitted under its respective credit facility.