XML 128 R98.htm IDEA: XBRL DOCUMENT v3.25.0.1

Employee Postretirement Benefits - Schedule of Composition of Periodic Benefit Cost (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2024	Dec. 31, 2023	Dec. 31, 2022
Retirement Benefits [Abstract]
Net Periodic Benefit Cost	$ (6,600)	$ (7,487)	$ 5,913
Net Amount Amortized Due to the Effect of Regulation	1,367	1,225	1,121
Net Periodic Benefit Cost Recognized	$ (5,233)	$ (6,262)	$ 7,034

X

- Definition

Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Deferred

+ References

No definition available.

+ Details

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

X

- Definition

Defined Benefit Plan, Net Periodic Benefit Cost (Credit), Net of Deferrals

+ References

No definition available.

+ Details

Name:	ottr_DefinedBenefitPlanNetPeriodicBenefitCostCreditNetOfDeferrals
Namespace Prefix:	ottr_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- References

No definition available.

+ Details

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

X

- Definition

Amount of net periodic benefit cost (credit) for defined benefit plan.

+ References

Reference 1: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 17
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480482/715-20-55-17

Reference 2: http://www.xbrl.org/2003/role/exampleRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 55
-Paragraph 18
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480482/715-20-55-18

Reference 3: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 1
-Subparagraph (h)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-1

Reference 4: http://www.xbrl.org/2003/role/disclosureRef
-Topic 715
-SubTopic 20
-Name Accounting Standards Codification
-Section 50
-Paragraph 6
-Subparagraph (a)
-Publisher FASB
-URI https://asc.fasb.org/1943274/2147480506/715-20-50-6

+ Details

Name:	us-gaap_DefinedBenefitPlanNetPeriodicBenefitCost
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration