Estimate of possible loss for each 10 basis point change to base ROE

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- Definition

Loss Contingency, Amount Associated With First Complaint Refunded

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- Definition

Loss Contingency, Base ROE Subsequently Authorized by FERC for First Complaint Period and Prospectively From October 2014

+ References

No definition available.

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- Definition

Loss Contingency, Basis Spread

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No definition available.

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- Definition

Loss Contingency, Maximum percentage of ROE for incentive projects

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- Definition

Loss Contingency, Percentage Of Base ROE Reasonably Justified

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No definition available.

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- Definition

Loss Contingency, Percentage Of Incentive Cap On Total ROE

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No definition available.

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- Definition

Loss Contingency, Percentage of ROE for Any Incentive Project

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No definition available.

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- Definition

Loss Contingency, Period of Complaint

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No definition available.

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- Definition

Percentage of Base ROE of Complaint Period

+ References

No definition available.

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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.

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- Definition

Reflects the estimated amount of loss from the specified contingency as of the balance sheet date.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
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-Name Accounting Standards Codification
-Topic 450
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-Section 50
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-Name Accounting Standards Codification
-Topic 460
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COMMITMENTS AND CONTINGENCIES - FERC ROE Complaints (Details) - USD ($) $ in Millions			3 Months Ended	6 Months Ended	36 Months Ended
	Apr. 29, 2016	Oct. 16, 2014	Jun. 30, 2019	Jun. 30, 2020	Oct. 15, 2014	Dec. 31, 2019
Loss Contingencies [Line Items]
Percentage of base ROE reasonably justified				10.41%
Percentage of incentive cap on total ROE				13.08%
FERC ROE First, Second and Third Complaints
Loss Contingencies [Line Items]
Base ROE subsequently authorized				11.14%
FERC ROE First, Second and Third Complaints \| Minimum
Loss Contingencies [Line Items]
Percentage of maximum ROE for any incentive project					11.14%
FERC ROE First, Second and Third Complaints \| Maximum
Loss Contingencies [Line Items]
Percentage of maximum ROE for any incentive project					13.10%
FERC ROE Complaints
Loss Contingencies [Line Items]
Period of complaint				15 months
Basis point change				0.10%
Estimate of possible loss for each 10 basis point change to base ROE				$ 3.0
FERC ROE Fourth Complaint
Loss Contingencies [Line Items]
Base ROE percentage of complaint period	10.57%
Maximum percentage cap of ROE for incentive projects	11.74%
FERC ROE First Complaint
Loss Contingencies [Line Items]
Base ROE subsequently authorized		10.57%
Percentage of maximum ROE for any incentive project		11.74%
Amounts associated with first complaint refunded				38.9
FERC ROE First Complaint \| CL&P
Loss Contingencies [Line Items]
Amounts associated with first complaint refunded				22.4
FERC ROE First Complaint \| NSTAR Electric
Loss Contingencies [Line Items]
Amounts associated with first complaint refunded				13.7
FERC ROE First Complaint \| PSNH
Loss Contingencies [Line Items]
Amounts associated with first complaint refunded				$ 2.8
FERC ROE Second Complaint
Loss Contingencies [Line Items]
Base ROE percentage of complaint period			10.57%
Percentage of maximum ROE for any incentive project				11.74%
Loss contingency, estimate of possible earnings impact				$ 39.1		$ 39.1
FERC ROE Second Complaint \| CL&P
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact				21.4		21.4
FERC ROE Second Complaint \| NSTAR Electric
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact				14.6		14.6
FERC ROE Second Complaint \| PSNH
Loss Contingencies [Line Items]
Loss contingency, estimate of possible earnings impact				$ 3.1		$ 3.1