LONG-TERM DEBT (Details) - USD ($) $ in Millions	6 Months Ended
Jun. 30, 2019	Jul. 24, 2019
WEC Energy Group \| WEC Senior Notes due 2022
Debt Instrument [Line Items]
Proceeds from Issuance of Debt	$ 350.0
Debt instrument stated interest rate percentage	3.10%
Subsequent event \| ATC Holding LLC \| ATC Holding Senior Notes due September 2029
Debt Instrument [Line Items]
Debt instrument stated interest rate percentage		3.75%
Secured commitment		$ 235.0

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

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Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

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The cash inflow during the period from additional borrowings in aggregate debt. Includes proceeds from short-term and long-term debt.

+ References

Reference 1: http://www.xbrl.org/2009/role/commonPracticeRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
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-Paragraph 14
-Subparagraph (b)
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