SHORT-TERM AND LONG-TERM DEBT	9 Months Ended
Sep. 30, 2016
Debt Disclosure [Abstract]
SHORT-TERM AND LONG-TERM DEBT	SHORT-TERM AND LONG-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 September 30, 2016 and December 31, 2015, Eversource parent had $698.5 million and approximately $1.1 billion, respectively, in short-term borrowings outstanding under the Eversource parent commercial paper program, leaving $751.5 million and $351.5 million of available borrowing capacity as of September 30, 2016 and December 31, 2015, respectively. The weighted-average interest rate on these borrowings as of September 30, 2016 and December 31, 2015 was 0.66 percent and 0.72 percent, respectively. As of September 30, 2016, there were intercompany loans from Eversource parent of $108.5 million to CL&P, $107.5 million to PSNH, and $48.2 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 September 30, 2016 or December 31, 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 September 30, 2016 and December 31, 2015, NSTAR Electric had $36.0 million and $62.5 million, respectively, in short-term borrowings outstanding under its commercial paper program, leaving $414.0 million and $387.5 million of available borrowing capacity as of September 30, 2016 and December 31, 2015, respectively. The weighted-average interest rate on these borrowings as of September 30, 2016 and December 31, 2015 was 0.42 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 September 30, 2016 or December 31, 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 parent to CL&P, PSNH and WMECO are eliminated in consolidation on Eversource’s balance sheets. Short-Term Borrowing Limits: The amount of short-term borrowings that may be incurred by NSTAR Electric is subject to periodic approval by the FERC. 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. Long-Term Debt Issuances: In March 2016, Eversource parent issued $250 million of 2.50 percent Series I Senior Notes due to mature in 2021 and $250 million of 3.35 percent Series J Senior Notes due to mature in 2026. The proceeds, net of issuance costs, were used to repay short-term borrowings under the Eversource parent commercial paper program. In May 2016, NSTAR Electric issued $250 million of 2.70 percent debentures, due to mature in 2026. The proceeds, net of issuance costs, were used to repay short-term borrowings under the NSTAR Electric commercial paper program and fund capital expenditures and working capital. In June 2016, WMECO issued $50 million of 2.75 percent Series H Senior Notes, due to mature in 2026. The proceeds, net of issuance costs, were used to repay short-term borrowings. Long-Term Debt Repayments: In May 2016, NSTAR Electric repaid at maturity $200 million variable rate debentures, using short-term borrowings.

SHORT-TERM AND LONG-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 September 30, 2016 and December 31, 2015, Eversource parent had $698.5 million and approximately $1.1 billion, respectively, in short-term borrowings outstanding under the Eversource parent commercial paper program, leaving $751.5 million and $351.5 million of available borrowing capacity as of September 30, 2016 and December 31, 2015, respectively. The weighted-average interest rate on these borrowings as of September 30, 2016 and December 31, 2015 was 0.66 percent and 0.72 percent, respectively. As of September 30, 2016, there were intercompany loans from Eversource parent of $108.5 million to CL&P, $107.5 million to PSNH, and $48.2 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 September 30, 2016 or December 31, 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 September 30, 2016 and December 31, 2015, NSTAR Electric had $36.0 million and $62.5 million, respectively, in short-term borrowings outstanding under its commercial paper program, leaving $414.0 million and $387.5 million of available borrowing capacity as of September 30, 2016 and December 31, 2015, respectively. The weighted-average interest rate on these borrowings as of September 30, 2016 and December 31, 2015 was 0.42 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 September 30, 2016 or December 31, 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 parent to CL&P, PSNH and WMECO are eliminated in consolidation on Eversource’s balance sheets.

Short-Term Borrowing Limits: The amount of short-term borrowings that may be incurred by NSTAR Electric is subject to periodic approval by the FERC. 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.

Long-Term Debt Issuances: In March 2016, Eversource parent issued $250 million of 2.50 percent Series I Senior Notes due to mature in 2021 and $250 million of 3.35 percent Series J Senior Notes due to mature in 2026. The proceeds, net of issuance costs, were used to repay short-term borrowings under the Eversource parent commercial paper program.

In May 2016, NSTAR Electric issued $250 million of 2.70 percent debentures, due to mature in 2026. The proceeds, net of issuance costs, were used to repay short-term borrowings under the NSTAR Electric commercial paper program and fund capital expenditures and working capital.

In June 2016, WMECO issued $50 million of 2.75 percent Series H Senior Notes, due to mature in 2026. The proceeds, net of issuance costs, were used to repay short-term borrowings.

Long-Term Debt Repayments: In May 2016, NSTAR Electric repaid at maturity $200 million variable rate debentures, using short-term borrowings.