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

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 15
-Subparagraph (b)
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LONG-TERM DEBT - Schedule of Long-term Debt Issuances and Repayments (Details) - USD ($) $ in Thousands	1 Months Ended	12 Months Ended
	Jan. 31, 2015	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016	Jan. 31, 2018
Debt Instrument [Line Items]
Repayments of debt		$ (1,050,330)	$ (745,000)	$ (200,000)
Eversource Parent 3.30% Series M Senior Notes
Debt Instrument [Line Items]
Interest rate stated percentage (up to) (as a percentage)					3.30%
Eversource Parent 1.60% Series G Senior Notes (5)
Debt Instrument [Line Items]
Interest rate stated percentage (up to) (as a percentage)	1.60%
The Connecticut Light And Power Company
Debt Instrument [Line Items]
Repayments of debt		(300,000)	(250,000)	0
NSTAR Electric Company
Debt Instrument [Line Items]
Repayments of debt		$ 0	(400,000)	(200,000)
NSTAR Electric Company \| Unsecured Debt \| Unsecured Notes Due 2027
Debt Instrument [Line Items]
Interest rate stated percentage (up to) (as a percentage)		3.20%
Public Service Company Of New Hampshire
Debt Instrument [Line Items]
Repayments of debt		$ (199,250)	(70,000)	0
Parent Company
Debt Instrument [Line Items]
Repayments of debt		$ (450,000)	$ 0	$ 0
Parent Company \| Senior Notes \| Eversource Parent 1.60% Series G Senior Notes (5)
Debt Instrument [Line Items]
Repayments of debt	$ (150,000)