XML 16 R79.htm IDEA: XBRL DOCUMENT
v3.20.1

OPUC (Details 2) - OPUC - Pending Rate Case [Member] - Gas Distribution [Member] - Cascade Natural Gas [Member] | Mar. 31, 2020 USD ($)
--- | ---
Public Utilities, General Disclosures [Line Items] |
Public Utilities, Requested Rate Increase (Decrease), Amount | $ 4,900,000
Public Utilities, Requested Rate Increase (Decrease), Percentage | 7.20%
Environmental Remediation Deferred Costs Increase (Decrease) Amount | $ 364,000

X
- Definition Environmental Remediation Deferred Costs Increase (Decrease) Amount + References No definition available. + Details
Name: | mdu_EnvironmentalRemediationDeferredCostsIncreaseDecreaseAmount
Namespace Prefix: | mdu_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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
- Definition Amount of public utility's requested rate increase (decrease) with regulatory agency. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesRequestedRateIncreaseDecreaseAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Percentage of public utility's requested rate increase (decrease) with regulatory agency. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesRequestedRateIncreaseDecreasePercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=mdu_PendingRateCaseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | dei_LegalEntityAxis=mdu_CascadeNaturalGasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |