XML 90 R78.htm IDEA: XBRL DOCUMENT
v3.21.2

FAIR VALUE MEASUREMENTS - ASSETS AND LIABILITIES MEASURED ON A RECURRING BASIS (Details) - USD ($) $ in Millions | Sep. 30, 2021 | Dec. 31, 2020
--- | --- | ---
Assets |  |
Derivative assets | $ 270.1 | $ 17.9
Liabilities |  |
Derivative liabilities | 22.3 | 22.1
Fair value measurements on a recurring basis |  |
Assets |  |
Derivative assets | 270.1 | 17.9
Investments held in rabbi trust | 77.8 | 79.6
Liabilities |  |
Derivative liabilities | 22.3 | 22.1
Fair value measurements on a recurring basis | Level 1 |  |
Assets |  |
Derivative assets | 209.6 | 11.7
Investments held in rabbi trust | 77.8 | 79.6
Liabilities |  |
Derivative liabilities | 0.1 | 7.7
Fair value measurements on a recurring basis | Level 2 |  |
Assets |  |
Derivative assets | 56.8 | 3.8
Investments held in rabbi trust | 0.0 | 0.0
Liabilities |  |
Derivative liabilities | 22.2 | 14.4
Fair value measurements on a recurring basis | Level 3 |  |
Assets |  |
Derivative assets | 3.7 | 2.4
Investments held in rabbi trust | 0.0 | 0.0
Liabilities |  |
Derivative liabilities | 0.0 | 0.0
Fair value measurements on a recurring basis | Natural gas contracts |  |
Assets |  |
Derivative assets | 222.2 | 13.7
Liabilities |  |
Derivative liabilities | 20.6 | 14.1
Fair value measurements on a recurring basis | Natural gas contracts | Level 1 |  |
Assets |  |
Derivative assets | 209.6 | 11.7
Liabilities |  |
Derivative liabilities | 0.1 | 7.7
Fair value measurements on a recurring basis | Natural gas contracts | Level 2 |  |
Assets |  |
Derivative assets | 12.6 | 2.0
Liabilities |  |
Derivative liabilities | 20.5 | 6.4
Fair value measurements on a recurring basis | Natural gas contracts | Level 3 |  |
Assets |  |
Derivative assets | 0.0 | 0.0
Liabilities |  |
Derivative liabilities | 0.0 | 0.0
Fair value measurements on a recurring basis | FTRs |  |
Assets |  |
Derivative assets | 3.7 | 2.4
Fair value measurements on a recurring basis | FTRs | Level 1 |  |
Assets |  |
Derivative assets | 0.0 | 0.0
Fair value measurements on a recurring basis | FTRs | Level 2 |  |
Assets |  |
Derivative assets | 0.0 | 0.0
Fair value measurements on a recurring basis | FTRs | Level 3 |  |
Assets |  |
Derivative assets | 3.7 | 2.4
Fair value measurements on a recurring basis | Coal contracts |  |
Assets |  |
Derivative assets | 44.2 | 1.8
Liabilities |  |
Derivative liabilities |  | 1.2
Fair value measurements on a recurring basis | Coal contracts | Level 1 |  |
Assets |  |
Derivative assets | 0.0 | 0.0
Liabilities |  |
Derivative liabilities |  | 0.0
Fair value measurements on a recurring basis | Coal contracts | Level 2 |  |
Assets |  |
Derivative assets | 44.2 | 1.8
Liabilities |  |
Derivative liabilities |  | 1.2
Fair value measurements on a recurring basis | Coal contracts | Level 3 |  |
Assets |  |
Derivative assets | 0.0 | 0.0
Liabilities |  |
Derivative liabilities |  | 0.0
Fair value measurements on a recurring basis | Interest rate swaps |  |
Liabilities |  |
Derivative liabilities | 1.7 | 6.8
Fair value measurements on a recurring basis | Interest rate swaps | Level 1 |  |
Liabilities |  |
Derivative liabilities | 0.0 | 0.0
Fair value measurements on a recurring basis | Interest rate swaps | Level 2 |  |
Liabilities |  |
Derivative liabilities | 1.7 | 6.8
Fair value measurements on a recurring basis | Interest rate swaps | Level 3 |  |
Liabilities |  |
Derivative liabilities | $ 0.0 | $ 0.0

X
- References No definition available. + Details
Name: | us-gaap_AssetsAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Fair value, before effects of master netting arrangements, of a financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes assets not subject to a master netting arrangement and elected not to be offset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 22 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313 + Details
Name: | us-gaap_DerivativeAssetFairValueGrossAssetIncludingNotSubjectToMasterNettingArrangement
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Fair value, before effects of master netting arrangements, of a financial liability or contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset. Includes liabilities not subject to a master netting arrangement and elected not to be offset. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=51824906&loc=SL20225862-175312 Reference 2: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 20 -Section 55 -Paragraph 22 -URI http://asc.fasb.org/extlink&oid=99393222&loc=SL20226052-175313 + Details
Name: | us-gaap_DerivativeLiabilityFairValueGrossLiabilityIncludingNotSubjectToMasterNettingArrangement
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Amount of restricted investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 954 -SubTopic 210 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=120413209&loc=SL6242269-115581 Reference 2: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 954 -SubTopic 210 -Section 45 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=120413173&loc=SL6242262-115580 Reference 3: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 860 -SubTopic 30 -Section 50 -Paragraph 1A -Subparagraph (b)(1)(i) -URI http://asc.fasb.org/extlink&oid=109249958&loc=SL6224234-111729 + Details
Name: | us-gaap_EquitySecuritiesFvNiRestricted
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- References No definition available. + Details
Name: | us-gaap_LiabilitiesAbstract
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_FairValueByMeasurementFrequencyAxis=us-gaap_FairValueMeasurementsRecurringMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel1Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel2Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=wec_CommodityContractNaturalGasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=wec_CommodityContractFinancialTransmissionRightsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_CoalContractMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DerivativeInstrumentRiskAxis=us-gaap_InterestRateSwapMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |