XML 157 R130.htm IDEA: XBRL DOCUMENT
v3.22.0.1

SDPUC (Details 3) | Nov. 15, 2021 USD ($)
--- | ---
SDPUC | Montana-Dakota Utilities Co. [Member] | Electricity [Member] |
Public Utilities, General Disclosures [Line Items] |
Total Infrastructure Rider | $ 0

X
- Definition Total Infrastructure Rider + References No definition available. + Details
Name: | mdu_TotalInfrastructureRider
Namespace Prefix: | mdu_
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_PublicUtilitiesGeneralDisclosuresLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RegulatoryAgencyAxis=mdu_SDPUCMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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