XML 163 R133.htm IDEA: XBRL DOCUMENT
v3.22.4

Jointly owned facilities (Details) - USD ($) $ in Thousands | Dec. 31, 2022 | Dec. 31, 2021
--- | --- | ---
Jointly owned electricity generation plant | Big Stone Station |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Proportionate ownership share | 22.70% |
Utility plant in service | $ 157,699 | $ 157,259
Construction work in progress | 231 | 571
Less accumulated depreciation | 48,590 | 47,293
Utility plant in services net | $ 109,340 | 110,537
Jointly owned electricity generation plant | Coyote Station |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Proportionate ownership share | 25.00% |
Utility plant in service | $ 158,274 | 157,764
Construction work in progress | 1,807 | 784
Less accumulated depreciation | 111,203 | 109,202
Utility plant in services net | $ 48,878 | 49,346
Jointly owned electricity generation plant | Wygen III |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Proportionate ownership share | 25.00% |
Utility plant in service | $ 66,238 | 66,357
Construction work in progress | 273 | 108
Less accumulated depreciation | 12,477 | 11,383
Utility plant in services net | $ 54,034 | 55,082
Jointly Owned Electricity Transmission and Distribution System | BSSE |  |
Jointly Owned Utility Plant Interests [Line Items] |  |
Proportionate ownership share | 50.00% |
Utility plant in service | $ 107,260 | 107,424
Construction work in progress | 0 | 0
Less accumulated depreciation | 6,182 | 4,506
Utility plant in services net | $ 101,078 | $ 102,918

X
- Definition The period end amount owned by the reporting utility of a jointly owned utility plant in service. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI https://asc.fasb.org/extlink&oid=122136288&loc=d3e659983-123033 + Details
Name: | us-gaap_JointlyOwnedUtilityPlantGrossOwnershipAmountOfPlantInService
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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_JointlyOwnedUtilityPlantInterestsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The total period end amount of plant in service and construction in progress net of accumulated depreciation for the utility's share of jointly owned electricity generation plant. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI https://asc.fasb.org/extlink&oid=122136288&loc=d3e659983-123033 + Details
Name: | us-gaap_JointlyOwnedUtilityPlantNetOwnershipAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The period end amount of construction work in progress at a jointly owned electricity generation plant. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI https://asc.fasb.org/extlink&oid=122136288&loc=d3e659983-123033 + Details
Name: | us-gaap_JointlyOwnedUtilityPlantOwnershipAmountOfConstructionWorkInProgress
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The period end amount of accumulated depreciation in a jointly owned electricity generation plant. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI https://asc.fasb.org/extlink&oid=122136288&loc=d3e659983-123033 + Details
Name: | us-gaap_JointlyOwnedUtilityPlantOwnershipAmountOfPlantAccumulatedDepreciation
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The proportionate share of interest (percent) in a jointly owned utility plant. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 360 -Section S99 -Paragraph 1 -Subparagraph (SAB Topic 10.C) -URI https://asc.fasb.org/extlink&oid=122136288&loc=d3e659983-123033 + Details
Name: | us-gaap_JointlyOwnedUtilityPlantProportionateOwnershipShare
Namespace Prefix: | us-gaap_
Data Type: | dtr-types:percentItemType
Balance Type: | na
Period Type: | instant

X
- Details
Name: | us-gaap_JointlyOwnedUtilityPlantAxis=us-gaap_JointlyOwnedElectricityGenerationPlantMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=mdu_BigStoneStationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=mdu_CoyoteStationMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=mdu_WygenIiiMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_JointlyOwnedUtilityPlantAxis=us-gaap_JointlyOwnedElectricityTransmissionAndDistributionSystemMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilityAxis=mdu_BSSEMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |