GOODWILL (Details) $ in Millions	3 Months Ended
Mar. 31, 2019 USD ($)
Goodwill
Changes to the carrying amount of goodwill	$ 0.0
Changes to our goodwill balances by segment
Goodwill balance by segment	3,052.8
Accumulated impairment losses	0.0
Wisconsin
Changes to our goodwill balances by segment
Goodwill balance by segment	2,104.3
Illinois
Changes to our goodwill balances by segment
Goodwill balance by segment	758.7
Other States
Changes to our goodwill balances by segment
Goodwill balance by segment	183.2
Non-Utility Energy Infrastructure
Changes to our goodwill balances by segment
Goodwill balance by segment	$ 6.6

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.

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

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