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SDPUC (Details 2) - SDPUC - Electricity [Member] - Montana-Dakota Utilities Co. [Member] - USD ($) | Apr. 28, 2022 | Mar. 01, 2022
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Subsequent Event [Member] |  |
Public Utilities, General Disclosures [Line Items] |  |
Total Infrastructure Rider | $ 940,000 |
Public Utilities, Approved Rate Increase (Decrease), Amount | $ (88,000) |
Pending Rate Case [Member] |  |
Public Utilities, General Disclosures [Line Items] |  |
Total Transmission Cost Adjustment Rider |  | $ 2,500,000
Transmission Capital Projects Increase (Decrease) |  | $ 1,500,000

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- Definition Total Infrastructure Rider + References No definition available. + Details
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Namespace Prefix: | mdu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Definition Total Transmission Cost Adjustment Rider + References No definition available. + Details
Name: | mdu_TotalTransmissionCostAdjustmentRider
Namespace Prefix: | mdu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Definition Transmission Capital Projects Increase (Decrease) + References No definition available. + Details
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Namespace Prefix: | mdu_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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- Definition Amount of public utility's approved rate increase (decrease) by regulatory agency. + References No definition available. + Details
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Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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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- Details
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Namespace Prefix: |
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- Details
Name: | us-gaap_PublicUtilityAxis=us-gaap_ElectricityMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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- Details
Name: | dei_LegalEntityAxis=mdu_MontanaDakotaUtilitiesCo.Member
Namespace Prefix: |
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- Details
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- Details
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Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |