XML 101 R74.htm IDEA: XBRL DOCUMENT
v3.22.0.1

Regulatory liabilities (Details 2) - USD ($) $ in Thousands | 12 Months Ended |
--- | --- | ---
Dec. 31, 2021 | Dec. 31, 2020
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities due within one year | $ 16,303 | $ 31,450
Regulatory liabilities | 428,790 | 428,075
Total regulatory liabilities | 445,093 | 459,525
Net Regulatory Position | $ 31,449 | (11,617)
Natural gas costs refundable through rate adjustments |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liability, refund period | Up to 1 year |
Regulatory liabilities due within one year | $ 6,700 | 18,565
Taxes refundable to customers |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities due within one year | 3,841 | 3,557
Regulatory liabilities | $ 215,421 | 227,850
Taxes refundable to customers | Minimum |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liability, refund period | Up to 1 year |
Taxes refundable to customers | Maximum |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liability, refund period | Over plant lives |
Electric fuel and purchased power deferral |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liability, refund period | Up to 1 year |
Regulatory liabilities due within one year | $ 0 | 3,667
Other regulatory liabilities |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liabilities due within one year | 5,762 | 5,661
Regulatory liabilities | $ 24,783 | 16,065
Other regulatory liabilities | Minimum |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liability, refund period | Up to 1 year |
Other regulatory liabilities | Maximum |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liability, refund period | Up to 20 years |
Plant removal and decommissioning costs |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liability, refund period | Over plant lives |
Regulatory liabilities | $ 168,152 | 167,171
Pension and postretirement benefits |  |
Regulatory Liabilities [Line Items] |  |
Regulatory liability, refund period | ** |
Regulatory liabilities | $ 20,434 | $ 16,989

X
- Definition regulatory liability, refund period + References No definition available. + Details
Name: | mdu_RegulatoryLiabilityRefundPeriod
Namespace Prefix: | mdu_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The net amount of all regulatory assets less all regulatory liabilities as of the end of the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
Name: | us-gaap_NetRegulatoryAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition The amount for the individual regulatory liability as itemized in a table of regulatory liabilities as of the end of the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 405 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394 + Details
Name: | us-gaap_RegulatoryLiabilities
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
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_RegulatoryLiabilitiesLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount for the individual regulatory current liability as itemized in a table of regulatory current liabilities as of the end of the period. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 405 -Section 25 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6500807&loc=d3e48068-110394 + Details
Name: | us-gaap_RegulatoryLiabilityCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Definition The amount for the individual regulatory noncurrent liability as itemized in a table of regulatory noncurrent liabilities as of the end of the period. + 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 210.5-02.24) -URI http://asc.fasb.org/extlink&oid=120391452&loc=d3e13212-122682 + Details
Name: | us-gaap_RegulatoryLiabilityNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | instant

X
- Details
Name: | us-gaap_RegulatoryLiabilityAxis=mdu_LiabilitiesRefundableGasCostsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_RegulatoryLiabilityAxis=mdu_ElectricFuelAndPurchasedPowerDeferralMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryLiabilityAxis=us-gaap_OtherRegulatoryAssetsLiabilitiesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryLiabilityAxis=us-gaap_RemovalCostsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryLiabilityAxis=us-gaap_PensionAndOtherPostretirementPlansCostsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |