XML 49 R37.htm IDEA: XBRL DOCUMENT
v3.22.2

Regulatory Matters - Regulatory Assets and Liabilities (Details) - USD ($) $ in Millions | 6 Months Ended |
--- | --- | ---
Jun. 30, 2022 | Dec. 31, 2021
Regulatory Assets and Liabilities [Line Items] |  |  |
Regulatory Assets Currently Earning a Return |  | With the exception of the regulatory asset for Boswell Units 1 and 2 net plant and equipment, no other regulatory assets are currently earning a return. |
Current Regulatory Assets | [1] | $ 39.8 | $ 0.0
Non-Current Regulatory Assets |  | 470.9 | 511.8
Regulatory Assets |  | 510.7 | 511.8
Current Regulatory Liabilities | [2] | 5.6 | 8.6
Non-Current Regulatory Liabilities |  | 532.6 | 536.1
Total Regulatory Liabilities |  | 538.2 | 544.7
Transmission Formula Rates [Member] |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Current Regulatory Liabilities | [2] | 4.5 | 3.1
Income Taxes [Member] |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Non-Current Regulatory Liabilities |  | 341.7 | 353.4
Wholesale and Retail Contra AFUDC [Member] |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Non-Current Regulatory Liabilities |  | 82.2 | 83.7
Plant Removal Obligations [Member] |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Non-Current Regulatory Liabilities |  | 56.9 | 52.6
Pension and Other Postretirement Plan Costs [Member] |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Non-Current Regulatory Liabilities |  | 25.0 | 28.1
North Dakota Investment Tax Credits [Member] |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Non-Current Regulatory Liabilities |  | 13.6 | 12.2
Other (Member) |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Current Regulatory Liabilities | [2] | 1.1 | 0.5
Non-Current Regulatory Liabilities |  | 10.4 | 5.7
Boswell Units 1 and 2 Net Plant and Equipment |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Non-Current Regulatory Liabilities |  | 2.8 | 0.4
Fuel Adjustment Clause [Member] |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Current Regulatory Liabilities | [2] | 0.0 | 5.0
Pension and Other Postretirement Plan Costs [Member] |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Non-Current Regulatory Assets |  | 220.1 | 226.4
Income Taxes [Member] |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Non-Current Regulatory Assets |  | 100.7 | 104.7
Cost Recovery Riders [Member] |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Non-Current Regulatory Assets |  | 49.9 | 63.2
Asset Retirement Obligations [Member] |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Non-Current Regulatory Assets |  | 34.2 | 33.1
Manufactured Gas Plant [Member] |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Non-Current Regulatory Assets |  | 17.6 | 17.0
PPACA Income Tax Deferral [Member] |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Non-Current Regulatory Assets |  | 4.2 | 4.3
Other (Member) |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Non-Current Regulatory Assets |  | 5.7 | 6.7
Fuel Adjustment Clause (Member) |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Current Regulatory Assets | [1] | 39.8 | 0.0
Non-Current Regulatory Assets |  | 34.7 | 56.4
Residential Customer Interim Rate Adjustment |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |
Non-Current Regulatory Assets |  | $ 3.8 | $ 0.0
[1] | Current regulatory assets are presented within Prepayments and Other on the Consolidated Balance Sheet.
[2] | Current regulatory liabilities are presented within Other Current Liabilities on the Consolidated Balance Sheet.

X
- Definition Regulatory Assets and Liabilities [Line Items] + References No definition available. + Details
Name: | ale_RegulatoryAssetsAndLiabilitiesLineItems
Namespace Prefix: | ale_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount for the individual regulatory asset as itemized in a table of regulatory assets 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 https://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
Name: | us-gaap_RegulatoryAssets
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are expected to be recovered through revenue sources within one year or the normal operating cycle, if longer. Such costs are capitalized if they meet both of the following criteria: a. It is probable that future revenue in an amount at least equal to the capitalized cost will result from inclusion of that cost in allowable costs for rate-making purposes. b. Based on available evidence, the future revenue will be provided to permit recovery of the previously incurred cost rather than to provide for expected levels of similar future costs. If the revenue will be provided through an automatic rate-adjustment clause, this criterion requires that the regulator's intent clearly be to permit recovery of the previously incurred cost. + 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 https://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
Name: | us-gaap_RegulatoryAssetsCurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Carrying amount as of the balance sheet date of capitalized costs of regulated entities that are not expected to be recovered through revenue sources within one year or the normal operating cycle if longer. + 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 https://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
Name: | us-gaap_RegulatoryAssetsNoncurrent
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 https://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 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 https://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 https://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
- Definition Identifies what net regulatory assets are earning a return through rate billings. + 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 https://asc.fasb.org/extlink&oid=6499975&loc=d3e44250-110382 + Details
Name: | us-gaap_TypesOfNetRegulatoryAssetsEarningReturns
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Details
Name: | us-gaap_RegulatoryLiabilityAxis=ale_TransmissionFormulaRatesMember
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=ale_WholesaleAndRetailContraAfudcMember
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: |

X
- Details
Name: | us-gaap_RegulatoryLiabilityAxis=ale_NorthDakotaInvestmentTaxCreditsSubjecttoRefundMember
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=ale_BoswellUnits1And2NetPlantAndEquipmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=ale_CostRecoveryRidersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=us-gaap_AssetRetirementObligationCostsMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=ale_ManufacturedGasPlantMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=ale_MedicarePartDRegulatoryAssetMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=us-gaap_RegulatoryClauseRevenuesUnderRecoveredMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RegulatoryAssetAxis=ale_ResidentialCustomerInterimRateAdjustmentMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |