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LONG-TERM DEBT (Details) - USD ($) $ in Millions |  | 3 Months Ended
--- | --- | ---
Mar. 30, 2020 | Mar. 31, 2021 | Mar. 31, 2020
Debt Instrument [Line Items] |  |  |
Issuance of short-term loan |  | $ 0.0 | $ 340.0
WEC Energy Group | Term loan |  |  |
Debt Instrument [Line Items] |  |  |
Issuance of short-term loan | $ 340.0 |  |
Length of term loan | 364 days |  |
WEC Energy Group | WEC Senior Notes 0.80% due 2024 |  |  |
Debt Instrument [Line Items] |  |  |
Proceeds from issuance of debt |  | $ 600.0 |
Debt instrument stated interest rate percentage |  | 0.80% |

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- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.22(a)(1)) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
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- Definition 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 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585 + Details
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- Definition Amount of cash inflow from short-term debt classified as other. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 230 -SubTopic 10 -Section 45 -Paragraph 14 -Subparagraph (b) -URI http://asc.fasb.org/extlink&oid=121586364&loc=d3e3255-108585 + Details
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- Definition Period of short-term debt issued. In 'PnYnMnDTnHnMnS' format, for example, P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. + References No definition available. + Details
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- Details
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