XML 83 R21.htm IDEA: XBRL DOCUMENT
v3.3.0.814

Pension and Other Postretirement Benefit Plans | 9 Months Ended
--- | ---
Sep. 30, 2015
Pension and Other Postretirement Benefit Plans [Abstract] |
Pension and Other Postretirement Benefit Plans [Text Block] | PENSION AND OTHER POSTRETIREMENT BENEFIT PLANS
| Pension |  | Other Postretirement
Components of Net Periodic Benefit Expense (Income) | 2015 |  | 2014 |  | 2015 |  | 2014
Millions |  |  |  |  |  |  |
Quarter Ended September 30, |  |  |  |  |  |  |
Service Cost | $2.6 |  |  |  | $2.0 |  |  | $1.0 |  |  |  | $0.9 |
Interest Cost | 7.5 |  |  | 7.5 |  |  | 1.8 |  |  | 1.8 |
Expected Return on Plan Assets | (10.2 | ) |  | (9.6 | ) |  | (2.7 | ) |  | (2.5 | )
Amortization of Prior Service Costs (Credits) | — |  |  | 0.1 |  |  | (0.7 | ) |  | (0.7 | )
Amortization of Net Loss | 4.4 |  |  | 3.6 |  |  | 0.1 |  |  | 0.1 |
Net Periodic Benefit Expense (Income) |  | $4.3 |  |  |  | $3.6 |  |  | $(0.5) |  | $(0.4)
Nine Months Ended September 30, |  |  |  |  |  |  |
Service Cost | $7.6 |  |  |  | $6.2 |  |  | $3.2 |  |  |  | $2.6 |
Interest Cost | 22.4 |  |  | 22.4 |  |  | 5.4 |  |  | 5.5 |
Expected Return on Plan Assets | (30.5 | ) |  | (28.7 | ) |  | (8.2 | ) |  | (7.7 | )
Amortization of Prior Service Costs (Credits) | 0.1 |  |  | 0.2 |  |  | (2.2 | ) |  | (1.9 | )
Amortization of Net Loss | 13.4 |  |  | 10.7 |  |  | 0.3 |  |  | 0.3 |
Net Periodic Benefit Expense (Income) |  | $13.0 |  |  |  | $10.8 |  |  | $(1.5) |  | $(1.2)
Employer Contributions. For the nine months ended September 30, 2015, no contributions were made to our defined benefit pension plan ($19.5 million for the nine months ended September 30, 2014); we do not expect to make any contributions to our defined benefit pension plan in 2015. For the nine months ended September 30, 2015 and 2014, we made no contributions to our other postretirement benefit plan; we do not expect to make any contributions to our other postretirement benefit plan in 2015.

X
- Definition Pension and Other Postretirement Benefit Plans [Abstract] + References No definition available. + Details
Name: | ale_PensionAndOtherPostretirementBenefitPlansAbstract
Namespace Prefix: | ale_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition The entire disclosure for pension and other postretirement benefits. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 80 -Section 50 -Paragraph 11 -URI http://asc.fasb.org/extlink&oid=49170332&loc=SL14450702-114947 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 20 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=58740216&loc=d3e2410-114920 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 60 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=6414203&loc=d3e39675-114964 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 70 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=49170846&loc=d3e28014-114942 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 715 -SubTopic 60 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6414199&loc=d3e39622-114963 + Details
Name: | us-gaap_PensionAndOtherPostretirementBenefitsDisclosureTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration