ACQUISITION OF AQUARION AND GOODWILL - Schedule of Goodwill by Reportable Segments (Details) $ in Thousands	12 Months Ended
Dec. 31, 2018 USD ($)
Goodwill [Roll Forward]
Beginning balance	$ 4,427,266
Goodwill	4,400,000
Ending balance	4,427,266
Electric Distribution
Goodwill [Roll Forward]
Goodwill	2,500,000
Electric Transmission
Goodwill [Roll Forward]
Goodwill	600,000
Natural Gas Distribution
Goodwill [Roll Forward]
Goodwill	400,000
Water Distribution
Goodwill [Roll Forward]
Goodwill	$ 900,000

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

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- Definition

Amount of increase (decrease) of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 50
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=108376223&loc=d3e13816-109267

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

+ References

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