XML 69 R60.htm IDEA: XBRL DOCUMENT
v2.4.0.8

Commitments, Guarantees and Contingencies - Power Purchase Agreements (Details) (USD $) | 9 Months Ended
--- | ---
Sep. 30, 2014 | Sep. 30, 2013
Square Butte PPA [Member] |  |
Power Purchase Agreements [Line Items] |  |
PPA Counterparty Debt Outstanding | $ 404,300,000 |
Annual Debt Service | 44,000,000 |
Power Purchased Under Long-term Contracts | 51,800,000 | 51,300,000
Interest Expense | 7,900,000 | 7,900,000
Square Butte PPA [Member] | Square Butte Coal-fired Unit [Member] |  |
Power Purchase Agreements [Line Items] |  |
Generating Capacity (MW) | 455 |
Output Entitlement | 50.00% |
Minnkota PPA [Member] |  |
Power Purchase Agreements [Line Items] |  |
Output Being Purchased (MW) | 50 |
Oliver Wind I PPA [Member] |  |
Power Purchase Agreements [Line Items] |  |
Output Being Purchased (MW) | 50 |
Term of Contract (Years) | 25 |
Fixed Capacity Charges | 0 |
Oliver Wind II PPA [Member] |  |
Power Purchase Agreements [Line Items] |  |
Output Being Purchased (MW) | 48 |
Term of Contract (Years) | 25 |
Fixed Capacity Charges | $ 0 |
Manitoba Hydro PPA (expires May2020) [Member] |  |
Power Purchase Agreements [Line Items] |  |
Output Being Purchased (MW) | 50 |
Manitoba Hydro PPA (expires April 2022) [Member] |  |
Power Purchase Agreements [Line Items] |  |
Output Being Purchased (MWh) | 1,000,000 |
Manitoba Hydro PPA (expires 2035) [Member] |  |
Power Purchase Agreements [Line Items] |  |
Output Being Purchased (MW) | 250 |
Term of Contract (Years) | 15 |
Manitoba Hydro PPA (expires 2040) [Member] |  |
Power Purchase Agreements [Line Items] |  |
Output Being Purchased (MW) | 133 |
Term of Contract (Years) | 20 |

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 Long-Term Contract for Purchase of Electric Power, Fixed Capacity Carges + References No definition available. + Details
Name: | ale_LongTermContractForPurchaseOfElectricPowerFixedCapacityCarges
Namespace Prefix: | ale_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | instant

X
- Definition Share of plant output being purchased in megawatts under a long-term contract to purchase electricity from a production plant constructed and financed by a public utility district, cooperative, or other organization. + References No definition available. + Details
Name: | ale_LongTermContractForPurchaseOfElectricPowerShareOfPlantOutputBeingPurchasedMw
Namespace Prefix: | ale_
Data Type: | num:powerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Share of plant output being purchased in megawatthours under a long-term contract to purchase electricity from a production plant constructed and financed by a public utility district, cooperative, or other organization. + References No definition available. + Details
Name: | ale_LongTermContractForPurchaseOfElectricPowerShareOfPlantOutputBeingPurchasedMwh
Namespace Prefix: | ale_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Term in years of long-term contract to purchase electricity from a production plant constructed and financed by a public utility district, cooperative, or other organization. + References No definition available. + Details
Name: | ale_LongTermContractForPurchaseOfElectricPowerTermOfContractYears
Namespace Prefix: | ale_
Data Type: | xbrli:integerItemType
Balance Type: | na
Period Type: | instant

X
- Definition Under long-term contracts with public utility districts, cooperatives or other organizations, a utility company receives a portion of the output of a production plant constructed and financed by the district or cooperative. The utility has only a nominal or no investment at all in the plant but pays a proportionate part of the plant's costs, including debt service. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 10.D) -URI http://asc.fasb.org/extlink&oid=6499423&loc=d3e659339-123030 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 10 -Section D + Details
Name: | us-gaap_LongTermContractForPurchaseOfElectricPowerAmountOfLongTermDebtOrLeaseObligationOutstanding
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Definition Under long-term contracts with public utility districts, cooperatives or other organizations, a utility company receives a portion of the output of a production plant constructed and financed by the district or cooperative. The utility has only a nominal or no investment at all in the plant but pays a proportionate part of the plant's costs, including debt service. If the utility is obligated to pay certain minimum amounts which cover debt service requirements whether or not the plant is operating, the amount can be disclosed here. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 10.D) -URI http://asc.fasb.org/extlink&oid=6499423&loc=d3e659339-123030 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 10 -Section D + Details
Name: | us-gaap_LongTermContractForPurchaseOfElectricPowerAnnualMinimumDebtServicePaymentRequired
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Definition The allocable portion of interest included in charges under a long-term contract to purchase electric power. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 10.D) -URI http://asc.fasb.org/extlink&oid=6499423&loc=d3e659339-123030 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 10 -Section D + Details
Name: | us-gaap_LongTermContractForPurchaseOfElectricPowerInterestIncludedInContractCharges
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration

X
- Details
Name: | us-gaap_LongTermContractForPurchaseOfElectricPowerLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Share of plant output being purchased under a long-term contract to purchase electricity from a production plant constructed and financed by a public utility district, cooperative, or other organization. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 10.D) -URI http://asc.fasb.org/extlink&oid=6499423&loc=d3e659339-123030 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Staff Accounting Bulletin (SAB) -Number Topic 10 -Section D + Details
Name: | us-gaap_LongTermContractForPurchaseOfElectricPowerShareOfPlantOutputBeingPurchased
Namespace Prefix: | us-gaap_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

X
- Definition Amount of operating expense for purchased power procured under arrangements extending beyond one year or the normal operating cycle, if longer, by regulated operation. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.2(b)) -URI http://asc.fasb.org/extlink&oid=26872669&loc=d3e20235-122688 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 980 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SAB TOPIC 10.D) -URI http://asc.fasb.org/extlink&oid=6499423&loc=d3e659339-123030 + Details
Name: | us-gaap_UtilitiesOperatingExpensePurchasedPowerUnderLongTermContracts
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration