INCOME TAXES (Details)	3 Months Ended
	Sep. 30, 2015
Other Tax Disclosures [Abstract]
Other Information Pertaining To Income Taxes	Part of the annual process in making adjustments to these estimates is reconciling the provision for income taxes made during the income tax estimation process to what was filed in the income tax return (return to provision). In the third quarter of 2015, Eversource and CL&P recorded an $8 million and $4.2 million charge, respectively, as a result of reconciling and adjusting its 2014 provision for income taxes to what was filed on its 2014 income tax return. Concurrently, Eversource and CL&P recorded a reversal of state tax reserves in the third quarter of 2015, which resulted in a $5.9 million and $2.2 million benefit, respectively.
The Connecticut Light And Power Company [Member]
Other Tax Disclosures [Abstract]
Other Information Pertaining To Income Taxes	Part of the annual process in making adjustments to these estimates is reconciling the provision for income taxes made during the income tax estimation process to what was filed in the income tax return (return to provision). In the third quarter of 2015, Eversource and CL&P recorded an $8 million and $4.2 million charge, respectively, as a result of reconciling and adjusting its 2014 provision for income taxes to what was filed on its 2014 income tax return. Concurrently, Eversource and CL&P recorded a reversal of state tax reserves in the third quarter of 2015, which resulted in a $5.9 million and $2.2 million benefit, respectively.