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Commitments and Contingencies (Details) - Otter Tail Power Company $ in Millions	Jun. 23, 2022 USD ($) MWh	Jun. 30, 2022 USD ($)
Other Commitments [Line Items]
Option exercised | MWh	62.4
Payments to acquire wind farm	$ 49.7
Federal Energy Regulatory Commission
Other Commitments [Line Items]
Estimated liability of refund obligation		$ 2.5

X

- Definition

Derivative, Nonmonetary, Energy Measure

+ References

No definition available.

+ Details

Name:	ottr_DerivativeNonmonetaryEnergyMeasure
Namespace Prefix:	ottr_
Data Type:	dtr-types:energyItemType
Balance Type:	na
Period Type:	duration

X

- 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

X

- Definition

Payments To Acquire Wind Farm

+ References

No definition available.

+ Details

Name:	ottr_PaymentsToAcquireWindFarm
Namespace Prefix:	ottr_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

X

- 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

Name:	us-gaap_OtherCommitmentsLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Details

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

X

- Details

Name:	us-gaap_RegulatoryAgencyAxis=ottr_FederalEnergyRegulatoryCommissionMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: