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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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