DERIVATIVE INSTRUMENTS - Changes in the Level 3 Category of Derivative Assets Measured at Fair Value on a Recurring Basis (Details) - CL&P - Level 3 - USD ($) $ in Millions	3 Months Ended
Mar. 31, 2022	Mar. 31, 2021
Derivatives, Net [Rollforward]
Fair Value as of Beginning of Period	$ (249.2)	$ (293.1)
Net Realized/Unrealized Gains/(Losses) Included in Regulatory Assets	6.2	(12.5)
Settlements	13.6	12.5
Fair Value as of End of Period	$ (229.4)	$ (293.1)

Fair Value Measurement With Unobservable Inputs Reconciliation Recurring Basis Asset Liability Gain (Loss) Included In Regulatory Asset Liability

No definition available.

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- Definition

Amount of settlements of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)(2)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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- Definition

Fair value of financial instrument classified as a liability measured using unobservable inputs that reflect the entity's own assumption about the assumptions market participants would use in pricing.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (c)
-URI http://asc.fasb.org/extlink&oid=123874694&loc=d3e19207-110258

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- Definition

A roll forward is a reconciliation of a concept from the beginning of a period to the end of a period.

+ References

No definition available.

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