XML 76 R66.htm IDEA: XBRL DOCUMENT
v3.23.1

Regulatory liabilities (Details 2) - USD ($) $ in Thousands | 3 Months Ended |  |
--- | --- | --- | ---
Mar. 31, 2023 | Dec. 31, 2022 | Mar. 31, 2022
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities due within one year | $ 44,395 | $ 26,440 | $ 31,186
Regulatory liabilities | 454,669 | 448,454 | 433,628
Total regulatory liabilities | 499,064 | 474,894 | 464,814
Net regulatory position | $ 66,754 | 19,857 | (16,508)
Electric fuel and purchased power deferral |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2023 | Up to 1 year |  |
Regulatory liabilities due within one year | $ 9,630 | 4,929 | 0
Natural gas costs refundable through rate adjustments |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2023 | Up to 1 year |  |
Regulatory liabilities due within one year | $ 6,331 | 955 | 13,107
Conservation programs |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2023 | Up to 1 year |  |
Regulatory liabilities due within one year | $ 3,834 | 4,126 | 144
Cost Recovery Mechanisms |  |  |
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities due within one year | 2,926 | 1,977 | 2,550
Regulatory liabilities | $ 16,313 | 14,025 | 9,508
Cost Recovery Mechanisms | Minimum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2023 | Up to 1 year |  |
Cost Recovery Mechanisms | Maximum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2023 | Up to 19 years |  |
Taxes refundable to customers |  |  |
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities due within one year | $ 1,513 | 3,937 | 3,470
Regulatory liabilities | $ 200,879 | 203,222 | 212,472
Taxes refundable to customers | Minimum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2023 | Up to 1 year |  |
Taxes refundable to customers | Maximum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2023 | Over plant lives |  |
Refundable Fuel and Electric Costs |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2023 | Up to 1 year |  |
Regulatory liabilities due within one year | $ 1,179 | 3,253 | 316
Other regulatory liabilities |  |  |
Regulatory Liabilities [Line Items] |  |  |
Regulatory liabilities due within one year | 18,982 | 7,263 | 11,599
Regulatory liabilities | $ 1,638 | 1,587 | 6,377
Other regulatory liabilities | Minimum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2023 | Up to 1 year |  |
Other regulatory liabilities | Maximum [Member] |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2023 | Up to 15 years |  |
Plant removal and decommissioning costs |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2023 | Over plant lives |  |
Regulatory liabilities | $ 214,467 | 208,650 | 171,485
Accumulated Deferred ITC |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2023 | Up to 19 years |  |
Regulatory liabilities | $ 13,996 | 13,594 | 13,352
Pension and postretirement benefits |  |  |
Regulatory Liabilities [Line Items] |  |  |
Estimated Recovery or Refund Period as of March 31, 2023 | ** |  |
Regulatory liabilities | $ 7,376 | $ 7,376 | $ 20,434

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 -Topic 980 -SubTopic 340 -Name Accounting Standards Codification -Section 50 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481878/980-340-50-1 + Details
Name: | us-gaap_NetRegulatoryAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Describes the continual or periodic assessment of the probability of future recovery of regulatory assets. + References Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef -Topic 980 -SubTopic 340 -Name Accounting Standards Codification -Section 25 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147482000/980-340-25-1 Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef -Name Accounting Standards Codification -Topic 980 -SubTopic 340 -Section 40 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481938/980-340-40-1 + Details
Name: | us-gaap_RegulatoryAssetRecoveryAssessments
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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 -Topic 980 -SubTopic 405 -Name Accounting Standards Codification -Section 25 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481854/980-405-25-1 + 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 -Topic 980 -SubTopic 405 -Name Accounting Standards Codification -Section 25 -Paragraph 1 -Publisher FASB -URI https://asc.fasb.org//1943274/2147481854/980-405-25-1 + 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 -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.24) -Publisher FASB -URI https://asc.fasb.org//1943274/2147480566/210-10-S99-1 + 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_LiabilitiesElectricFuelAndPurchasedPowerDeferralMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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_RenewableEnergyProgramMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_RegulatoryLiabilityAxis=mdu_RefundableFuelAndElectricCostsMember
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=mdu_AccumulatedDeferredITCMember
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: |