XML 64 R51.htm IDEA: XBRL DOCUMENT
v3.5.0.2

Regulatory Matters - Utility Rates (Details) $ in Millions |  |  |  | 6 Months Ended
--- | --- | --- | --- | ---
Jun. 28, 2016 USD ($) | Jan. 01, 2013 | Jun. 01, 2011 | Jun. 30, 2016 USD ($) Customers Years MW | Jun. 30, 2015 USD ($)
Minnesota Power [Member] | Bison Wind Energy Center [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
Generating Capacity (MW) | MW |  |  |  | 497 |
PSCW [Member] | 2012 Wisconsin Rate Case [Member] | SWL&P [Member] | Retail [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
Approved Return on Common Equity |  | 10.90% |  |  |
PSCW [Member] | 2016 Wisconsin Rate Case [Member] | SWL&P [Member] | Retail [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
Requested Rate Increase (Decrease) | 3.10% |  |  |  |
Requested Return on Equity | 10.90% |  |  |  |
Requested Equity Capital Structure | 55.00% |  |  |  |
Requested Debt Capital Structure | 45.00% |  |  |  |
Annual Additional Revenue Generated from Overall Requested Rate Increase | $ | $ 2.7 |  |  |  |
Electric Rates [Member] | MPUC [Member] | 2010 Minnesota Rate Case [Member] | Minnesota Power [Member] | Retail [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
Approved Return on Common Equity |  |  | 10.38% |  |
Approved Equity Ratio |  |  | 54.29% |  |
Electric Rates [Member] | MPUC [Member] | Minnesota Cost Recovery Riders [Member] | Minnesota Power [Member] | Retail [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
Revenue from Cost Recovery Riders | $ |  |  |  | $ 48.9 | $ 44.9
Electric Rates [Member] | MPUC [Member] | Renewable Cost Recovery Rider [Member] | Minnesota Power [Member] | Retail [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
North Dakota Investment Tax Credits | $ |  |  |  | 8.0 |
Electric Rates [Member] | MPUC [Member] | Annual Automatic Adjustment of Charges [Member] | Minnesota Power [Member] | Retail [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
Retail Fuel Cost Recovery Collected but Subject to Refund | $ |  |  |  | $ 350.0 |
Electric Rates [Member] | FERC [Member] | FERC-Approved Wholesale Rates [Member] | Minnesota Power [Member] | Municipal Customers [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
Number of Customers | Customers |  |  |  | 16 |
Length of Notice Required to Terminate Contract (Years) | Years |  |  |  | 3 |
Electric Rates [Member] | FERC [Member] | FERC-Approved Wholesale Rates [Member] | Minnesota Power [Member] | Municipal Customers [Member] | Wholesale Electric Contracts (Expire December 2024) [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
Number of Customers | Customers |  |  |  | 14 |
Electric Rates [Member] | FERC [Member] | FERC-Approved Wholesale Rates [Member] | Minnesota Power [Member] | Municipal Customers [Member] | Wholesale Electric Contracts (Expire December 2024) [Member] | Maximum [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
Change in Annual Capacity Charge Per Contract - Percentage |  |  |  | 2.00% |
Electric Rates [Member] | FERC [Member] | FERC-Approved Wholesale Rates [Member] | Minnesota Power [Member] | Municipal Customers [Member] | Wholesale Electric Contracts (Expire December 2024) [Member] | Minimum [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
Change in Annual Capacity Charge Per Contract - Percentage |  |  |  | (1.00%) |
Electric Rates [Member] | FERC [Member] | FERC-Approved Wholesale Rates [Member] | Minnesota Power [Member] | Municipal Customers [Member] | Wholesale Electric Contract (Termination Effective June 2019) [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
Number of Customers | Customers |  |  |  | 1 |
Average Monthly Demand (MW) | MW |  |  |  | 29 |
Electric Rates [Member] | FERC [Member] | FERC-Approved Wholesale Rates [Member] | Minnesota Power [Member] | Municipal Customers [Member] | Wholesale Electric Contract (Cost-Based Formula Methodology for Entire Term) [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
Number of Customers | Customers |  |  |  | 3 |
Electric Rates [Member] | PSCW [Member] | 2016 Wisconsin Rate Case [Member] | SWL&P [Member] | Retail [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
Requested Rate Increase (Decrease) | 3.50% |  |  |  |
Natural Gas Rates [Member] | PSCW [Member] | 2016 Wisconsin Rate Case [Member] | SWL&P [Member] | Retail [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
Requested Rate Increase (Decrease) | (1.30%) |  |  |  |
Water Rates [Member] | PSCW [Member] | 2016 Wisconsin Rate Case [Member] | SWL&P [Member] | Retail [Member] |  |  |  |  |
Regulatory Matters [Line Items] |  |  |  |  |
Requested Rate Increase (Decrease) | 7.80% |  |  |  |

X
- Definition Retail fuel cost recovery collected but subject to refund per Annual Automatic Adjustment (AAA) of Charges filings currently outstanding with the MPUC. + References No definition available. + Details
Name: | ale_AAARetailFuelCostRecovery
Namespace Prefix: | ale_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Average demand measured for a specified customer, measured in MW. + References No definition available. + Details
Name: | ale_AverageCustomerDemandMW
Namespace Prefix: | ale_
Data Type: | num:powerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The annual percentage change of the capacity charge specified in a power purchase, power sales, or electric sales agreement. + References No definition available. + Details
Name: | ale_ChangeinAnnualCapacityChargePerContractPercentage
Namespace Prefix: | ale_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | instant

X
- Definition Capacity of a generating facility, unit, or project in megawatts. + References No definition available. + Details
Name: | ale_GeneratingCapacityMw
Namespace Prefix: | ale_
Data Type: | num:powerItemType
Balance Type: | na
Period Type: | instant

X
- Definition The length of notice required to terminate a contract (in years). + References No definition available. + Details
Name: | ale_LengthOfNoticeRequiredToTerminateYears
Namespace Prefix: | ale_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Number of Customers + References No definition available. + Details
Name: | ale_NumberOfCustomers
Namespace Prefix: | ale_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Amount before allocation of valuation allowances of deferred tax asset attributable to other deductible tax credit carryforwards not separately disclosed. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 3 -Subparagraph (a) -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32559-109319 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 8 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32632-109319 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 740 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32621-109319 + Details
Name: | us-gaap_DeferredTaxAssetsTaxCreditCarryforwardsOther
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Percentage of public utility's approved equity to capital, including debt and equity. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesApprovedEquityCapitalStructurePercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of public utility's approved return on equity. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesApprovedReturnOnEquityPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
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 Percentage of public utility's requested debt to capital, including debt and equity. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesRequestedDebtCapitalStructurePercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Percentage of public utility's requested equity to capital, including debt and equity. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesRequestedEquityCapitalStructurePercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
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
- Definition Percentage of public utility's requested return on equity. + References No definition available. + Details
Name: | us-gaap_PublicUtilitiesRequestedReturnOnEquityPercentage
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition The amount of regulated other operating revenues recognized during the period. + References No definition available. + Details
Name: | us-gaap_RegulatedOperatingRevenueOther
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

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

X
- Details
Name: | ale_GeneratingFacilityAxisAxis=ale_BisonWindEnergyCenterMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=ale_A2012WisconsinRateCaseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | ale_CustomerClassAxis=ale_RetailCustomersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=ale_A2016WisconsinRateCaseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ale_RateTypeAxis=ale_ElectricRatesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

X
- Details
Name: | us-gaap_PublicUtilitiesRegulatoryProceedingAxis=ale_A2010RateCaseMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

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

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

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

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

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

X
- Details
Name: | ale_CustomerClassAxis=ale_MunicipalCustomersMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ale_LongtermContractsforSaleofElectricPowerAxis=ale_WholesaleElectricContractsExpireDecember2024Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ale_LongtermContractsforSaleofElectricPowerAxis=ale_WholesaleElectricContractTerminationEffectiveJune2019Member
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ale_LongtermContractsforSaleofElectricPowerAxis=ale_WholesaleElectricContractCostBasedFormulaMethodologyforEntireTermMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ale_RateTypeAxis=ale_NaturalGasRatesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | ale_RateTypeAxis=ale_WaterRatesMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |