Face (par) amount of debt instrument at time of issuance.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
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- Definition

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

+ References

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))
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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

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)
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-Name Accounting Standards Codification
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- Definition

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

+ References

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-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
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-Paragraph 15
-Subparagraph (b)
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SHORT-TERM AND LONG-TERM DEBT - Schedule of Issuances and Repayments (Details) - USD ($)	1 Months Ended				9 Months Ended
	Oct. 31, 2018	Jan. 31, 2015	May 31, 2013	May 31, 2008	Sep. 30, 2018	Sep. 30, 2017	Jan. 31, 2018
Debt Instrument [Line Items]
Repayments					$ (860,855,000)	$ (320,000,000)
Senior Notes \| Series O First Mortgage Bonds
Debt Instrument [Line Items]
Issuances					50,000,000.0
Senior Notes \| Series P First Mortgage Bonds
Debt Instrument [Line Items]
Issuances					100,000,000.0
The Connecticut Light and Power Company
Debt Instrument [Line Items]
Repayments					(300,000,000)	(250,000,000)
The Connecticut Light and Power Company \| Senior Notes \| 2018 Series A First Mortgage Bonds
Debt Instrument [Line Items]
Issuances					$ 500,000,000
Interest rate, stated percentage					4.00%
The Connecticut Light and Power Company \| Senior Notes \| 2008 Series A First Mortgage Bonds
Debt Instrument [Line Items]
Repayments				$ (300,000,000)
Interest rate, stated percentage				5.65%
Public Service Company of New Hampshire
Debt Instrument [Line Items]
Repayments					$ (110,000,000)	$ (70,000,000)
Public Service Company of New Hampshire \| Senior Notes \| 2008 Series O First Mortgage Bonds
Debt Instrument [Line Items]
Repayments				$ (110,000,000)
Interest rate, stated percentage				6.00%
Eversource Parent \| Senior Notes \| Eversource Parent Series I Senior Notes
Debt Instrument [Line Items]
Issuances							$ 200,000,000.0
Long-term debt					$ 450,000,000
Interest rate, stated percentage							2.50%
Eversource Parent \| Senior Notes \| Series M Senior Notes
Debt Instrument [Line Items]
Issuances							$ 450,000,000.0
Interest rate, stated percentage							3.30%
Eversource Parent \| Senior Notes \| Series G Senior Notes
Debt Instrument [Line Items]
Repayments		$ (150,000,000)
Interest rate, stated percentage		1.60%
Eversource Parent \| Senior Notes \| Series E Senior Notes
Debt Instrument [Line Items]
Repayments			$ (300,000,000)
Interest rate, stated percentage			1.45%
Eversource Parent \| Senior Notes \| Series O First Mortgage Bonds
Debt Instrument [Line Items]
Interest rate, stated percentage			4.13%
Eversource Parent \| Senior Notes \| Series P First Mortgage Bonds
Debt Instrument [Line Items]
Interest rate, stated percentage					4.09%
Subsequent Event \| Senior Notes \| Series J Senior Notes Due 2018
Debt Instrument [Line Items]
Repayments	$ (100,000,000)
Interest rate, stated percentage	6.90%