LONG-TERM DEBT	9 Months Ended
Sep. 30, 2012
Notes To Consolidated Financial Statements [Abstract]
Long-term Debt [Text Block]	8. LONG-TERM DEBT (NU, CL&P, NSTAR Electric, WMECO) On March 22, 2012, NU parent issued $300 million of floating rate Series D Senior Notes with a maturity date of September 20, 2013. The notes have a coupon rate based on the three-month LIBOR rate plus a credit spread of 0.75 percent and will reset quarterly. The notes had an interest rate of 1.13 percent as of September 30, 2012. The proceeds, net of issuance expenses, were used to repay at maturity the NU parent $263 million Series A Senior Notes that matured on April 1, 2012, to repay short-term borrowings outstanding under the NU parent Credit Agreement and for other general corporate purposes. The indenture under which the bonds were issued requires NU to comply with certain covenants as are customarily included in such indentures. On April 2, 2012, CL&P remarketed $62 million of tax-exempt PCRBs for a three-year period. The PCRBs, which mature on May 1, 2031, carry a coupon rate of 1.55 percent during the current three-year fixed rate period and are subject to mandatory tender for purchase on April 1, 2015. On April 2, 2012, NU parent repaid its $263 million 7.25 percent Series A Senior Notes that matured on April 1, 2012 with the proceeds from the issuance of floating rate Series D Senior Notes issued on March 22, 2012. In addition, as a result of consolidating CYAPC and YAEC, NU has consolidated $179.5 million in additional spent nuclear fuel obligations as of September 30, 2012. The spent nuclear fuel obligation is payable to the DOE at any time prior to the first delivery to the DOE of spent nuclear fuel and radio-active waste used to generate electricity prior to April 7, 1983. Until payment is made to the DOE, the outstanding liability will continue to accrue interest at the 3-month Treasury bill yield rate. NU, including CL&P, NSTAR Electric, PSNH and WMECO, was in compliance with all its debt covenants as of September 30, 2012. On October 1, 2012, CL&P redeemed at par four different series of tax-exempt PCRBs totaling $116.4 million. The PCRBs carried coupons that ranged from 5.85 percent to 5.95 percent and maturities that ranged from 2016 through 2028. On October 1, 2012, WMECO redeemed at par $53.8 million of tax-exempt PCRBs. The PCRBs had a maturity date of 2028 and a coupon of 5.85 percent. On October 4, 2012, WMECO issued at a premium $150 million of senior unsecured notes at a yield of 2.673 percent that will mature on September 15, 2021. The senior unsecured notes are part of the same series of WMECO's existing 3.5 percent coupon Series F Notes that were initially issued in September 2011. As a result, the aggregate principal amount of WMECO's outstanding Series F Notes totaled $250 million. On October 15, 2012, NSTAR Electric issued at a discount $400 million of 2.375 percent Debentures at a yield of 2.406 percent that will mature on October 15, 2022. The proceeds were used to pay $400 million of 4.875 percent Debentures that matured on October 15, 2012.

LONG-TERM DEBT

9 Months Ended

Sep. 30, 2012

Notes To Consolidated Financial Statements [Abstract]

8. LONG-TERM DEBT (NU, CL&P, NSTAR Electric, WMECO)

On March 22, 2012, NU parent issued $300 million of floating rate Series D Senior Notes with a maturity date of September 20, 2013. The notes have a coupon rate based on the three-month LIBOR rate plus a credit spread of 0.75 percent and will reset quarterly. The notes had an interest rate of 1.13 percent as of September 30, 2012. The proceeds, net of issuance expenses, were used to repay at maturity the NU parent $263 million Series A Senior Notes that matured on April 1, 2012, to repay short-term borrowings outstanding under the NU parent Credit Agreement and for other general corporate purposes. The indenture under which the bonds were issued requires NU to comply with certain covenants as are customarily included in such indentures.

On April 2, 2012, CL&P remarketed $62 million of tax-exempt PCRBs for a three-year period. The PCRBs, which mature on May 1, 2031, carry a coupon rate of 1.55 percent during the current three-year fixed rate period and are subject to mandatory tender for purchase on April 1, 2015.

On April 2, 2012, NU parent repaid its $263 million 7.25 percent Series A Senior Notes that matured on April 1, 2012 with the proceeds from the issuance of floating rate Series D Senior Notes issued on March 22, 2012.

In addition, as a result of consolidating CYAPC and YAEC, NU has consolidated $179.5 million in additional spent nuclear fuel obligations as of September 30, 2012. The spent nuclear fuel obligation is payable to the DOE at any time prior to the first delivery to the DOE of spent nuclear fuel and radio-active waste used to generate electricity prior to April 7, 1983. Until payment is made to the DOE, the outstanding liability will continue to accrue interest at the 3-month Treasury bill yield rate.

NU, including CL&P, NSTAR Electric, PSNH and WMECO, was in compliance with all its debt covenants as of September 30, 2012.

On October 1, 2012, CL&P redeemed at par four different series of tax-exempt PCRBs totaling $116.4 million. The PCRBs carried coupons that ranged from 5.85 percent to 5.95 percent and maturities that ranged from 2016 through 2028. On October 1, 2012, WMECO redeemed at par $53.8 million of tax-exempt PCRBs. The PCRBs had a maturity date of 2028 and a coupon of 5.85 percent.

On October 4, 2012, WMECO issued at a premium $150 million of senior unsecured notes at a yield of 2.673 percent that will mature on September 15, 2021. The senior unsecured notes are part of the same series of WMECO's existing 3.5 percent coupon Series F Notes that were initially issued in September 2011. As a result, the aggregate principal amount of WMECO's outstanding Series F Notes totaled $250 million.

On October 15, 2012, NSTAR Electric issued at a discount $400 million of 2.375 percent Debentures at a yield of 2.406 percent that will mature on October 15, 2022. The proceeds were used to pay $400 million of 4.875 percent Debentures that matured on October 15, 2012.