XML 63 R56.htm IDEA: XBRL DOCUMENT
v2.4.1.9

Regulatory Matters - Regulatory Assets and Liabilities (Details) (USD $) In Millions, unless otherwise specified | 12 Months Ended |
--- | --- | ---
Dec. 31, 2014 | Dec. 31, 2013
Regulatory Assets and Liabilities [Line Items] |  |  |  |
Current Regulatory Asset | $ 16.3 us-gaap_RegulatoryAssetsCurrent |  | $ 23.0 us-gaap_RegulatoryAssetsCurrent |
Non-Current Regulatory Asset | 357.3 us-gaap_RegulatoryAssetsNoncurrent |  | 263.8 us-gaap_RegulatoryAssetsNoncurrent |
Total Regulatory Assets | 373.6 us-gaap_RegulatoryAssets |  | 286.8 us-gaap_RegulatoryAssets |
Non-Current Regulatory Liability | 94.2 us-gaap_RegulatoryLiabilityNoncurrent |  | 81.0 us-gaap_RegulatoryLiabilityNoncurrent |
Types of Net Regulatory Assets Earning Returns | No regulatory assets or liabilities are currently earning a return. |  |  |
Wholesale and Retail Contra AFUDC [Member] |  |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |  |
Non-Current Regulatory Liability | 42.9 us-gaap_RegulatoryLiabilityNoncurrent / us-gaap_RegulatoryLiabilityAxis = ale_WholesaleAndRetailContraAfudcMember |  | 19.7 us-gaap_RegulatoryLiabilityNoncurrent / us-gaap_RegulatoryLiabilityAxis = ale_WholesaleAndRetailContraAfudcMember |
Plant Removal Obligations [Member] |  |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |  |
Non-Current Regulatory Liability | 22.8 us-gaap_RegulatoryLiabilityNoncurrent / us-gaap_RegulatoryLiabilityAxis = us-gaap_RemovalCostsMember |  | 19.7 us-gaap_RegulatoryLiabilityNoncurrent / us-gaap_RegulatoryLiabilityAxis = us-gaap_RemovalCostsMember |
Income Taxes [Member] |  |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |  |
Non-Current Regulatory Liability | 13.4 us-gaap_RegulatoryLiabilityNoncurrent / us-gaap_RegulatoryLiabilityAxis = us-gaap_DeferredIncomeTaxChargesMember |  | 17.0 us-gaap_RegulatoryLiabilityNoncurrent / us-gaap_RegulatoryLiabilityAxis = us-gaap_DeferredIncomeTaxChargesMember |
Defined Benefit Pension and Other Postretirement Plans [Member] |  |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |  |
Non-Current Regulatory Liability | 3.5 us-gaap_RegulatoryLiabilityNoncurrent / us-gaap_RegulatoryLiabilityAxis = us-gaap_PensionAndOtherPostretirementPlansCostsMember | [1] | 16.3 us-gaap_RegulatoryLiabilityNoncurrent / us-gaap_RegulatoryLiabilityAxis = us-gaap_PensionAndOtherPostretirementPlansCostsMember | [1]
Other [Member] |  |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |  |
Non-Current Regulatory Liability | 11.6 us-gaap_RegulatoryLiabilityNoncurrent / us-gaap_RegulatoryLiabilityAxis = us-gaap_OtherRegulatoryAssetsLiabilitiesMember |  | 8.3 us-gaap_RegulatoryLiabilityNoncurrent / us-gaap_RegulatoryLiabilityAxis = us-gaap_OtherRegulatoryAssetsLiabilitiesMember |
Deferred Fuel Adjustment Clause [Member] |  |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |  |
Current Regulatory Asset | 16.3 us-gaap_RegulatoryAssetsCurrent / us-gaap_RegulatoryAssetAxis = us-gaap_DeferredFuelCostsMember | [2] | 23.0 us-gaap_RegulatoryAssetsCurrent / us-gaap_RegulatoryAssetAxis = us-gaap_DeferredFuelCostsMember | [2]
Defined Benefit Pension and Other Postretirement Plans [Member] |  |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |  |
Non-Current Regulatory Asset | 223.9 us-gaap_RegulatoryAssetsNoncurrent / us-gaap_RegulatoryAssetAxis = us-gaap_PensionAndOtherPostretirementPlansCostsMember | [1] | 164.1 us-gaap_RegulatoryAssetsNoncurrent / us-gaap_RegulatoryAssetAxis = us-gaap_PensionAndOtherPostretirementPlansCostsMember | [1]
Income Taxes [Member] |  |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |  |
Non-Current Regulatory Asset | 46.6 us-gaap_RegulatoryAssetsNoncurrent / us-gaap_RegulatoryAssetAxis = us-gaap_DeferredIncomeTaxChargesMember |  | 35.3 us-gaap_RegulatoryAssetsNoncurrent / us-gaap_RegulatoryAssetAxis = us-gaap_DeferredIncomeTaxChargesMember |
Asset Retirement Obligation [Member] |  |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |  |
Non-Current Regulatory Asset | 17.8 us-gaap_RegulatoryAssetsNoncurrent / us-gaap_RegulatoryAssetAxis = us-gaap_AssetRetirementObligationCostsMember |  | 16.0 us-gaap_RegulatoryAssetsNoncurrent / us-gaap_RegulatoryAssetAxis = us-gaap_AssetRetirementObligationCostsMember |
Cost Recovery Riders [Member] |  |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |  |
Non-Current Regulatory Asset | 59.7 us-gaap_RegulatoryAssetsNoncurrent / us-gaap_RegulatoryAssetAxis = ale_CurrentCostRecoveryRiderMember | [3] | 39.6 us-gaap_RegulatoryAssetsNoncurrent / us-gaap_RegulatoryAssetAxis = ale_CurrentCostRecoveryRiderMember | [3]
PPACA Income Tax Deferral [Member] |  |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |  |
Non-Current Regulatory Asset | 5.0 us-gaap_RegulatoryAssetsNoncurrent / us-gaap_RegulatoryAssetAxis = ale_MedicarePartDRegulatoryAssetMember |  | 5.0 us-gaap_RegulatoryAssetsNoncurrent / us-gaap_RegulatoryAssetAxis = ale_MedicarePartDRegulatoryAssetMember |
Other [Member] |  |  |  |
Regulatory Assets and Liabilities [Line Items] |  |  |  |
Non-Current Regulatory Asset | $ 4.3 us-gaap_RegulatoryAssetsNoncurrent / us-gaap_RegulatoryAssetAxis = us-gaap_OtherRegulatoryAssetsLiabilitiesMember |  | $ 3.8 us-gaap_RegulatoryAssetsNoncurrent / us-gaap_RegulatoryAssetAxis = us-gaap_OtherRegulatoryAssetsLiabilitiesMember |
[1] | Defined benefit pension and other postretirement items included in our Regulated Operations, which are otherwise required to be recognized in accumulated other comprehensive income, are recognized as regulatory assets or regulatory liabilities on the Consolidated Balance Sheet. (See Note 17. Pension and Other Postretirement Benefit Plans.)
[2] | Current regulatory assets are included in Prepayments and Other on the Consolidated Balance Sheet.
[3] | The cost recovery rider regulatory assets are due to capital expenditures related to our Bison Wind Energy Center, investment in CapX2020 projects, and the Boswell Unit 4 environmental upgrade and are recognized in accordance with the accounting standards for alternative revenue programs.

X
- 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://www.xbrl.org/2003/role/presentationRef -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_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://www.xbrl.org/2003/role/presentationRef -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_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://www.xbrl.org/2003/role/presentationRef -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_RegulatoryAssetsNoncurrent
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
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://www.xbrl.org/2003/role/presentationRef -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=6877327&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://www.xbrl.org/2003/role/presentationRef -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_TypesOfNetRegulatoryAssetsEarningReturns
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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

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