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LONG TERM DEBT (Details) - USD ($) $ in Millions		9 Months Ended
	Oct. 15, 2018	Sep. 30, 2018
Integrys Holding | Integrys 2006 Junior Notes due 2066
Debt Instrument [Line Items]
Extinguishment of debt		$ 114.9
WE
Debt Instrument [Line Items]
Long-term Pollution Control Bond		$ 80.0
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 | WE 4.30% Debentures due 2048
Debt Instrument [Line Items]
Proceeds from Issuance of Debt	$ 300.0
Debt instrument stated interest rate percentage	4.30%
Subsequent event | PGL | PGL Series FFF Bonds due 2028
Debt Instrument [Line Items]
Secured commitments	$ 150.0
Subsequent event | NSG | NSG Series R Bonds due 2028
Debt Instrument [Line Items]
Secured commitments	$ 50.0
WEC Energy Group | WEC 2007 Junior Notes due 2067
Debt Instrument [Line Items]
Long-term debt outstanding		500.0
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
Interest rate swaps | WEC Energy Group
Debt Instrument [Line Items]
Interest rate swap notional value		$ 250.0
Interest rate swap fixed interest rate		4.9765%

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