Contractual interest rate for funds borrowed, under the debt agreement.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

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The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

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SHORT-TERM AND LONG-TERM DEBT - Summary of Long-Term Debt Issuance and Repayments (Details) - USD ($) $ in Thousands		1 Months Ended	3 Months Ended
	Feb. 01, 2019	Apr. 30, 2019	Mar. 31, 2019	Mar. 31, 2018	Feb. 01, 2009
Debt Instrument [Line Items]
Repayments			$ (250,215)	$ (150,218)
CL&P
Debt Instrument [Line Items]
Repayments			(250,000)	$ 0
CL&P \| Senior Notes \| 4.00% 2018 Series A First Mortgage Bonds \| Subsequent Event
Debt Instrument [Line Items]
Issuances		$ 300,000
Interest rate, stated percentage		4.00%
CL&P \| Senior Notes \| 4.00% 2018 Series A First Mortgage Bonds \| Eversource Parent
Debt Instrument [Line Items]
Long-term debt			$ 800,000
CL&P \| Senior Notes \| 5.50% 2009 Series A First Mortgage Bonds
Debt Instrument [Line Items]
Repayments	$ (250,000)
Interest rate, stated percentage					5.65%