XML 73 R60.htm IDEA: XBRL DOCUMENT v3.3.0.814

Regulatory Matters - MISO Return on Equity Complaints (Details) $ in Millions	Sep. 30, 2015 USD ($)
FERC Complaint 1 [Member]
Loss Contingencies [Line Items]
Proposed Return on Common Equity	9.15%
FERC Complaint 2 [Member]
Loss Contingencies [Line Items]
Proposed Return on Common Equity	8.67%
Minnesota Power [Member]
Loss Contingencies [Line Items]
Estimated Refund for MISO Revenue	$ 6.2
Estimated Refund for MISO Transmission Expense	4.1
Reserve	2.1
Reserve, Portion Attributable to Prior Years	$ 1.5

X

- Definition

The proposed return on common equity, which would be dedicated to the utility plant in the investee accounted for under the equity method of accounting.

+ References

No definition available.

+ Details

Name:	ale_EquityMethodInvestmentProposedReturnonCommonEquity
Namespace Prefix:	ale_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

X

- Definition

Estimated Refund

+ References

No definition available.

+ Details

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

X

- Definition

Estimated Refund Obligation

+ References

No definition available.

+ Details

Name:	ale_EstimatedRefundObligation
Namespace Prefix:	ale_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

X

- Definition

Amount of a loss contingency accrual recorded in the current current but attributable to prior years.

+ References

No definition available.

+ Details

Name:	ale_LossContingencyAccrualAttributabletoPriorYears
Namespace Prefix:	ale_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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_LossContingenciesLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Amount of loss contingency liability.

+ References

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



-Publisher FASB



-Name Accounting Standards Codification



-Topic 450



-SubTopic 20



-Section 50



-Paragraph 1



-URI http://asc.fasb.org/extlink&oid=25496072&loc=d3e14326-108349

+ Details

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

X

- Details

Name:	ale_FERCComplaintAxis=ale_FERCComplaint1Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	ale_FERCComplaintAxis=ale_FERCComplaint2Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

X

- Details

Name:	dei_LegalEntityAxis=ale_MinnesotaPowerMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: