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LONG TERM DEBT (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2018	Jul. 31, 2018	Jul. 12, 2018
Integrys Holding | Integrys 2006 Junior Notes due 2066
Debt Instrument [Line Items]
Extinguishment of debt	$ 114.9
WE | WE Debentures due 2018
Debt Instrument [Line Items]
Debt instrument stated interest rate percentage	1.70%
Extinguishment of debt	$ 250.0
Subsequent event | WE
Debt Instrument [Line Items]
Long-term Pollution Control Bond		$ 80.0
WEC Energy Group | WEC 3.375% Senior Notes due June 15, 2021
Debt Instrument [Line Items]
Proceeds from Issuance of Debt	$ 600.0
Debt instrument stated interest rate percentage	3.375%
WEC Energy Group | WEC Senior Notes due 2018
Debt Instrument [Line Items]
Debt instrument stated interest rate percentage	1.65%
Extinguishment of debt	$ 300.0
WEC Energy Group | WEC 2007 Junior Notes due 2067
Debt Instrument [Line Items]
Long-term debt outstanding	$ 500.0
Interest Rate Swap | WEC Energy Group | Subsequent event
Debt Instrument [Line Items]
Interest rate swap notional value			$ 250.0
Interest rate swap fixed interest rate			4.9765%

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- Definition

Aggregate notional amount specified by the derivative(s). Expressed as an absolute value.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher SEC
-Name Regulation S-X (SX)
-Number 210
-Article 12
-Section 13
-Sentence Column B

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Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02.22(a)(1))
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+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
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-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

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