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Commitments and Contingencies (Details) - Otter Tail Power Company $ in Millions | 1 Months Ended |
--- | --- | ---
Mar. 31, 2024 plan | Jun. 30, 2024 USD ($)
Federal Energy Regulatory Commission |  |
Other Commitments [Line Items] |  |
Estimated liability of refund obligation | $ |  | $ 2.9
Environmental Protection Agency |  |
Other Commitments [Line Items] |  |
Number of outstanding state implementation plans, timeline provided by regulatory agency | plan | 34 |

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- Definition This element represents amount of estimated liability for FERC ordered MISO tariff ROE refund obligation. + References No definition available. + Details
Name: | ottr_EstimatedLiabilityOfRefundObligation
Namespace Prefix: | ottr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

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- Definition Number of Outstanding State Implementation Plans, Timeline Provided By Regulatory Agency + References No definition available. + Details
Name: | ottr_NumberOfOutstandingStateImplementationPlansTimelineProvidedByRegulatoryAgency
Namespace Prefix: | ottr_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | duration

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | dei_LegalEntityAxis=ottr_OtterTailPowerCompanyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | us-gaap_RegulatoryAgencyAxis=ottr_EnvironmentalProtectionAgencyMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |