XML 99 R75.htm IDEA: XBRL DOCUMENT
v3.22.4

Short-Term and Long-Term Borrowings - Narrative (Details) - USD ($) | 12 Months Ended |  |
--- | --- | --- | ---
Dec. 31, 2022 | Dec. 31, 2021 | Oct. 31, 2022 | Jun. 10, 2021
Debt Instrument [Line Items] |  |  |  |
Line of credit facility, maximum borrowing capacity | $ 340,000,000 |  |  |
Debt, weighted average interest rate (as a percent) | 5.61% | 1.42% |  |
Senior Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Aggregate principal amount |  |  |  | $ 230,000,000
Proceeds from issuance of debt | $ 90,000,000 | $ 140,000,000 |  |
Minimum |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Interest and dividend coverage ratio | 1.50 |  |  |
Minimum | Benchmark rate |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt instrument, basis spread on variable rate | 0.00% |  |  |
Maximum |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt to total capitalization ratio | 60.00% |  |  |
Maximum | Benchmark rate |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Debt instrument, basis spread on variable rate | 2.00% |  |  |
OTC Credit Agreement |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Line of credit facility, maximum borrowing capacity | $ 170,000,000 |  |  |
Line of credit facility, increased current borrowing capacity, accordion provision |  |  | $ 290,000,000 |
OTP Credit Agreement |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Line of credit facility, maximum borrowing capacity | $ 170,000,000 |  |  |
Line of credit facility, increased current borrowing capacity, accordion provision |  |  | 250,000,000 |
Series 2021A Senior Unsecured Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Rate (as a percent) | 2.74% |  |  |
Series 2021A Senior Unsecured Notes | Senior Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Aggregate principal amount |  |  |  | $ 40,000,000
Rate (as a percent) |  |  |  | 2.74%
Series 2021B Senior Unsecured Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Rate (as a percent) | 3.69% |  |  |
Series 2021B Senior Unsecured Notes | Senior Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Aggregate principal amount |  |  |  | $ 100,000,000
Rate (as a percent) |  |  |  | 3.69%
Series 2022A Senior Unsecured Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Rate (as a percent) | 3.77% |  |  |
Series 2022A Senior Unsecured Notes | Senior Notes |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Aggregate principal amount |  |  |  | $ 90,000,000
Rate (as a percent) |  |  |  | 3.77%
Revolving Credit Facility | OTC Credit Agreement |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Line of credit facility, maximum borrowing capacity |  |  | 170,000,000 |
Revolving Credit Facility | OTP Credit Agreement |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Line of credit facility, maximum borrowing capacity |  |  | 170,000,000 |
Letter of Credit | OTC Credit Agreement |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Line of credit facility, maximum borrowing capacity |  |  | 40,000,000 |
Letter of Credit | OTP Credit Agreement |  |  |  |
Debt Instrument [Line Items] |  |  |  |
Line of credit facility, maximum borrowing capacity |  |  | $ 50,000,000 |

X
- Definition Represents the required ratio of debt to total capitalization. + References No definition available. + Details
Name: | ottr_DebtToTotalCapitalizationRatio
Namespace Prefix: | ottr_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Represents the required interest and dividend coverage ratio. + References No definition available. + Details
Name: | ottr_InterestAndDividendCoverageRatio
Namespace Prefix: | ottr_
Data Type: | xbrli:pureItemType
Balance Type: | na
Period Type: | instant

X
- Definition Line of Credit Facility, Increased Current Borrowing Capacity, Accordion Provision + References No definition available. + Details
Name: | ottr_LineOfCreditFacilityIncreasedCurrentBorrowingCapacityAccordionProvision
Namespace Prefix: | ottr_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Percentage points added to the reference rate to compute the variable rate on the debt instrument. + References No definition available. + Details
Name: | us-gaap_DebtInstrumentBasisSpreadOnVariableRate1
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Face (par) amount of debt instrument at time of issuance. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1B -Subparagraph (a) -URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 45 -Paragraph 2 -URI https://asc.fasb.org/extlink&oid=124435984&loc=d3e28551-108399 Reference 3: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 55 -Paragraph 8 -URI https://asc.fasb.org/extlink&oid=114775985&loc=d3e28878-108400 Reference 4: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 835 -SubTopic 30 -Section 50 -Paragraph 1 -URI https://asc.fasb.org/extlink&oid=124429444&loc=SL124452920-239629 Reference 5: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69C -URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495737-112612 Reference 6: http://www.xbrl.org/2003/role/exampleRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 55 -Paragraph 69B -URI https://asc.fasb.org/extlink&oid=123466577&loc=SL123495735-112612 + Details
Name: | us-gaap_DebtInstrumentFaceAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition Contractual interest rate for funds borrowed, under the debt agreement. + References Reference 1: http://www.xbrl.org/2003/role/disclosureRef -Publisher FASB -Name Accounting Standards Codification -Topic 470 -SubTopic 20 -Section 50 -Paragraph 1B -Subparagraph (b) -URI https://asc.fasb.org/extlink&oid=123466505&loc=SL123495323-112611 Reference 2: 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 https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_DebtInstrumentInterestRateStatedPercentage
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

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_DebtInstrumentLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Weighted average interest rate of debt outstanding. + References No definition available. + Details
Name: | us-gaap_DebtWeightedAverageInterestRate
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility. + 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 210.5-02.19(b),22(b)) -URI https://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_LineOfCreditFacilityMaximumBorrowingCapacity
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The cash inflow from a borrowing with the highest claim on the assets of the entity in case of bankruptcy or liquidation (with maturities initially due after one year or beyond the operating cycle, if longer). + 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 https://asc.fasb.org/extlink&oid=126954810&loc=d3e3255-108585 + Details
Name: | us-gaap_ProceedsFromIssuanceOfSeniorLongTermDebt
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_LongtermDebtTypeAxis=us-gaap_SeniorNotesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_VariableRateAxis=ottr_BenchmarkRateMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | srt_RangeAxis=srt_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=ottr_OtterTailCorporationCreditAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=ottr_OTPCreditAgreementMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=ottr_SeniorUnsecuredNotes274SeriesADueNovember292031Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=ottr_SeniorUnsecuredNotes369SeriesBDueNovember292051Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_DebtInstrumentAxis=ottr_SeniorUnsecuredNotes377SeriesADueMay202052Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_CreditFacilityAxis=us-gaap_LetterOfCreditMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |