XML 103 R10.htm IDEA: XBRL DOCUMENT
v3.3.0.814

Investments | 9 Months Ended
--- | ---
Sep. 30, 2015
Schedule of Investments [Line Items] |
Investments | INVESTMENTS Unconsolidated Equity Investments - Equity (income) loss from unconsolidated investments accounted for under the equity method of accounting for the three and nine months ended September 30 was as follows (in millions):
| Alliant Energy |  | WPL
| Three Months |  | Nine Months |  | Three Months |  | Nine Months
| 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
ATC |  | ($10.9 | ) |  |  | ($11.2 | ) |  |  | ($29.6 | ) |  |  | ($33.5 | ) |  |  | ($10.9 | ) |  |  | ($11.2 | ) |  |  | ($29.6 | ) |  |  | ($33.5 | )
Other | (0.2 | ) |  | (0.3 | ) |  | 0.7 |  |  | (0.7 | ) |  | (0.2 | ) |  | (0.2 | ) |  | (0.6 | ) |  | (0.7 | )
|  | ($11.1 | ) |  |  | ($11.5 | ) |  |  | ($28.9 | ) |  |  | ($34.2 | ) |  |  | ($11.1 | ) |  |  | ($11.4 | ) |  |  | ($30.2 | ) |  |  | ($34.2 | )
WPL [Member] |
Schedule of Investments [Line Items] |
Investments | INVESTMENTS Unconsolidated Equity Investments - Equity (income) loss from unconsolidated investments accounted for under the equity method of accounting for the three and nine months ended September 30 was as follows (in millions):
| Alliant Energy |  | WPL
| Three Months |  | Nine Months |  | Three Months |  | Nine Months
| 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014 |  | 2015 |  | 2014
ATC |  | ($10.9 | ) |  |  | ($11.2 | ) |  |  | ($29.6 | ) |  |  | ($33.5 | ) |  |  | ($10.9 | ) |  |  | ($11.2 | ) |  |  | ($29.6 | ) |  |  | ($33.5 | )
Other | (0.2 | ) |  | (0.3 | ) |  | 0.7 |  |  | (0.7 | ) |  | (0.2 | ) |  | (0.2 | ) |  | (0.6 | ) |  | (0.7 | )
|  | ($11.1 | ) |  |  | ($11.5 | ) |  |  | ($28.9 | ) |  |  | ($34.2 | ) |  |  | ($11.1 | ) |  |  | ($11.4 | ) |  |  | ($30.2 | ) |  |  | ($34.2 | )

X
- Definition The entire disclosure for investment holdings. This includes the long positions of investments for the entity. It contains investments in affiliated and unaffiliated issuers. The investments include securities and non securities (i.e. commodities and futures contracts). + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 4 -Subparagraph (SX 210.12-12C) -URI http://asc.fasb.org/extlink&oid=34726532&loc=d3e611225-123010 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 6 -Subparagraph (SX 210.12-14) -URI http://asc.fasb.org/extlink&oid=34726532&loc=d3e611322-123010 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 5 -Subparagraph (SX 210.12-13) -URI http://asc.fasb.org/extlink&oid=34726532&loc=d3e611282-123010 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 946 -SubTopic 320 -Section S99 -Paragraph 1 -Subparagraph (SX 210.12-12) -URI http://asc.fasb.org/extlink&oid=34726532&loc=d3e611133-123010 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 12 -Article 12 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 12C -Article 12 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 13 -Article 12 + Details
Name: | us-gaap_InvestmentHoldingsTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

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

X
- Details
Name: | dei_LegalEntityAxis=lnt_WplMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |