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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No definition available.

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- Definition

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.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 470
-SubTopic 20
-Section 50
-Paragraph 4
-Subparagraph (b)(3)
-URI http://asc.fasb.org/extlink&oid=109500613&loc=SL6031897-161870

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
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-URI http://asc.fasb.org/extlink&oid=119400593&loc=d3e572229-122910

Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

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

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 14
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3255-108585

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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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-Publisher FASB
-Name Accounting Standards Codification
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-SubTopic 10
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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					9 Months Ended
	Feb. 01, 2019	Sep. 30, 2019	Jul. 31, 2019	Jun. 30, 2019	May 31, 2019	Apr. 30, 2019	Sep. 30, 2019	Sep. 30, 2018	Feb. 01, 2009
Debt Instrument [Line Items]
Repayments							$ (250,855)	$ (860,855)
CL&P
Debt Instrument [Line Items]
Repayments							(250,000)	(300,000)
CL&P \| Senior Notes \| 4.00% 2018 Series A First Mortgage Bonds
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					$ 800,000
CL&P \| Senior Notes \| 3.20% 2017 Series A First Mortgage Bonds
Debt Instrument [Line Items]
Issuances		$ 200,000
Interest rate, stated percentage		3.20%					3.20%
CL&P \| Senior Notes \| 3.20% 2017 Series A First Mortgage Bonds \| Eversource Parent
Debt Instrument [Line Items]
Long-term debt		$ 500,000					$ 500,000
CL&P \| Senior Notes \| 5.50% 2009 Series A First Mortgage Bonds
Debt Instrument [Line Items]
Repayments	$ (250,000)
Interest rate, stated percentage									5.50%
NSTAR Electric \| Senior Notes \| 3.25% 2019 Debentures
Debt Instrument [Line Items]
Issuances					$ 400,000
Interest rate, stated percentage					3.25%
PSNH
Debt Instrument [Line Items]
Repayments							$ 0	$ (110,000)
PSNH \| Senior Notes \| 3.60% 2019 Series T First Mortgage Bonds
Debt Instrument [Line Items]
Issuances				$ 300,000
Interest rate, stated percentage				3.60%
NSTAR Gas \| Senior Notes \| NSTAR Gas 3.74% Series Q First Mortgage Bonds
Debt Instrument [Line Items]
Issuances			$ 75,000
Interest rate, stated percentage			3.74%
NSTAR Gas \| Senior Notes \| Yankee Gas 2.23% Series P First Mortgage Bonds
Debt Instrument [Line Items]
Interest rate, stated percentage		2.23%					2.23%
NSTAR Gas \| Senior Notes \| Yankee Gas 3.30% Series Q First Mortgage Bonds
Debt Instrument [Line Items]
Interest rate, stated percentage		3.30%					3.30%
Yankee Gas \| Senior Notes \| Yankee Gas 2.23% Series P First Mortgage Bonds
Debt Instrument [Line Items]
Issuances		$ 100,000
Yankee Gas \| Senior Notes \| Yankee Gas 3.30% Series Q First Mortgage Bonds
Debt Instrument [Line Items]
Issuances		$ 100,000