XML 74 R66.htm IDEA: XBRL DOCUMENT v2.4.0.8

Commitments, Guarantees and Contingencies - Environmental Matters (Details) (USD $) In Millions, unless otherwise specified	3 Months Ended
	Sep. 30, 2014 MW	Jun. 30, 2014
Boswell Unit 4 [Member]
Environmental Matters [Line Items]
Estimated Capital Expenditures, Including Past Expenditures	$ 250
Capital Cost Spent to Date	120
Other Commitment, Due in Next Twelve Months	103
Other Commitment, Due in Second Year	75
NOV Consent Decree [Member]
Environmental Matters [Line Items]
Environmental Remediation Expense	4.2
Civil Penalty		1.4
Estimated Capital Expenditures, Including Past Expenditures	600
Generating Capacity (MW)	200
NOV Consent Decree [Member] | Minimum [Member]
Environmental Matters [Line Items]
Estimated Capital Expenditures	20
NOV Consent Decree [Member] | Maximum [Member]
Environmental Matters [Line Items]
Estimated Capital Expenditures	$ 40

X

- Definition

Capital cost spent to date for project.

+ References

No definition available.

+ Details

Name:	ale_CapitalCostSpentToDate
Namespace Prefix:	ale_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Civil Penalty

+ References

No definition available.

+ Details

Name:	ale_CivilPenalty
Namespace Prefix:	ale_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Details

Name:	ale_EnvironmentalMattersLineItems
Namespace Prefix:	ale_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

The estimated amount of certain future capital expenditures related to environmental compliance, regulatory matters, or other committments and/or contingencies.

+ References

No definition available.

+ Details

Name:	ale_EstimatedCapitalExpenditures
Namespace Prefix:	ale_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

The estimated amount of certain capital expenditures related to environmental compliance, regulatory matters, or other commitments and/or contingencies. This estimate includes expenditures expected in future periods and expenditures made through the end of the current period.

+ References

No definition available.

+ Details

Name:	ale_EstimatedCapitalExpendituresIncludingPastExpenditures
Namespace Prefix:	ale_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
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 charge against earnings in the period for known or estimated future costs arising from requirements to perform environmental remediation activities.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 230

-SubTopic 10

-Section 45

-Paragraph 28

-URI http://asc.fasb.org/extlink&oid=31042434&loc=d3e3602-108585



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 410

-SubTopic 30

-Section 50

-Paragraph 12

-URI http://asc.fasb.org/extlink&oid=6393242&loc=d3e13296-110859

+ Details

Name:	us-gaap_EnvironmentalRemediationExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

X

- Definition

Minimum amount of other commitment maturing in the next fiscal year following the latest fiscal year for commitments not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in this taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

+ References

No definition available.

+ Details

Name:	us-gaap_OtherCommitmentDueInNextTwelveMonths
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Minimum amount of other commitment maturing in the second fiscal year following the latest fiscal year for commitments not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in this taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

+ References

No definition available.

+ Details

Name:	us-gaap_OtherCommitmentDueInSecondYear
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant