XML 78 R36.htm IDEA: XBRL DOCUMENT
v3.6.0.2

Investments (Tables) | 12 Months Ended
--- | ---
Dec. 31, 2016
Investment [Line Items] |
Unconsolidated Equity Investments | Alliant Energy’s and WPL’s unconsolidated investments accounted for under the equity method of accounting are as follows (in millions):
| Ownership Interest at |  | Carrying Value at December 31, |  | Equity (Income) / Loss
| December 31, 2016 |  | 2016 |  | 2015 |  | 2016 |  | 2015 |  | 2014
Alliant Energy |  |  |  |  |  |  |  |  |  |  |
ATC (a) | 16% |  |  | $317.6 |  |  |  | $293.3 |  |  |  | ($39.1 | ) |  |  | ($34.2 | ) |  |  | ($41.9 | )
Other | Various |  | 8.4 |  |  | 9.6 |  |  | (0.5 | ) |  | 0.4 |  |  | 1.5 |
|  |  |  | $326.0 |  |  |  | $302.9 |  |  |  | ($39.6 | ) |  |  | ($33.8 | ) |  |  | ($40.4 | )
WPL |  |  |  |  |  |  |  |  |  |  |
ATC | —% |  |  | $— |  |  |  | $293.3 |  |  |  | ($39.1 | ) |  |  | ($34.2 | ) |  |  | ($41.9 | )
Wisconsin River Power Company | 50% |  | 7.7 |  |  | 8.7 |  |  | (0.7 | ) |  | (0.9 | ) |  | (0.9 | )
|  |  |  | $7.7 |  |  |  | $302.0 |  |  |  | ($39.8 | ) |  |  | ($35.1 | ) |  |  | ($42.8 | )
(a) | Alliant Energy currently has the ability to exercise significant influence over ATC’s financial and operating policies through its participation on ATC’s Board of Directors. Refer to Note 18 for information regarding related party transactions with ATC.
Summary Financial Information | Summary aggregate financial information from the financial statements of these investments is as follows (in millions):
| Alliant Energy |  | WPL
| 2016 |  | 2015 |  | 2014 |  | 2016 |  | 2015 |  | 2014
Operating revenues |  | $658 |  |  |  | $624 |  |  |  | $643 |  |  |  | $658 |  |  |  | $624 |  |  |  | $643 |
Operating income | 331 |  |  | 299 |  |  | 330 |  |  | 331 |  |  | 299 |  |  | 330 |
Net income | 232 |  |  | 186 |  |  | 240 |  |  | 234 |  |  | 202 |  |  | 240 |
As of December 31: |  |  |  |  |  |  |  |  |  |  |
Current assets | 82 |  |  | 88 |  |  |  |  | 6 |  |  | 87 |  |  |
Non-current assets | 4,340 |  |  | 3,987 |  |  |  |  | 19 |  |  | 3,977 |  |  |
Current liabilities | 498 |  |  | 332 |  |  |  |  | 3 |  |  | 332 |  |  |
Non-current liabilities | 2,144 |  |  | 2,052 |  |  |  |  | 7 |  |  | 2,052 |  |  |
Cash Surrender Value of Life Insurance Policies | At December 31, the cash surrender value of these investments was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2016 |  | 2015 |  | 2016 |  | 2015 |  | 2016 |  | 2015
Cash surrender value | $10.6 |  | $42.3 |  | $— |  | $18.9 |  | $5.8 |  | $6.4
IPL [Member] |
Investment [Line Items] |
Cash Surrender Value of Life Insurance Policies | At December 31, the cash surrender value of these investments was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2016 |  | 2015 |  | 2016 |  | 2015 |  | 2016 |  | 2015
Cash surrender value | $10.6 |  | $42.3 |  | $— |  | $18.9 |  | $5.8 |  | $6.4
WPL [Member] |
Investment [Line Items] |
Unconsolidated Equity Investments | Alliant Energy’s and WPL’s unconsolidated investments accounted for under the equity method of accounting are as follows (in millions):
| Ownership Interest at |  | Carrying Value at December 31, |  | Equity (Income) / Loss
| December 31, 2016 |  | 2016 |  | 2015 |  | 2016 |  | 2015 |  | 2014
Alliant Energy |  |  |  |  |  |  |  |  |  |  |
ATC (a) | 16% |  |  | $317.6 |  |  |  | $293.3 |  |  |  | ($39.1 | ) |  |  | ($34.2 | ) |  |  | ($41.9 | )
Other | Various |  | 8.4 |  |  | 9.6 |  |  | (0.5 | ) |  | 0.4 |  |  | 1.5 |
|  |  |  | $326.0 |  |  |  | $302.9 |  |  |  | ($39.6 | ) |  |  | ($33.8 | ) |  |  | ($40.4 | )
WPL |  |  |  |  |  |  |  |  |  |  |
ATC | —% |  |  | $— |  |  |  | $293.3 |  |  |  | ($39.1 | ) |  |  | ($34.2 | ) |  |  | ($41.9 | )
Wisconsin River Power Company | 50% |  | 7.7 |  |  | 8.7 |  |  | (0.7 | ) |  | (0.9 | ) |  | (0.9 | )
|  |  |  | $7.7 |  |  |  | $302.0 |  |  |  | ($39.8 | ) |  |  | ($35.1 | ) |  |  | ($42.8 | )
(a) | Alliant Energy currently has the ability to exercise significant influence over ATC’s financial and operating policies through its participation on ATC’s Board of Directors. Refer to Note 18 for information regarding related party transactions with ATC.
Summary Financial Information | Summary aggregate financial information from the financial statements of these investments is as follows (in millions):
| Alliant Energy |  | WPL
| 2016 |  | 2015 |  | 2014 |  | 2016 |  | 2015 |  | 2014
Operating revenues |  | $658 |  |  |  | $624 |  |  |  | $643 |  |  |  | $658 |  |  |  | $624 |  |  |  | $643 |
Operating income | 331 |  |  | 299 |  |  | 330 |  |  | 331 |  |  | 299 |  |  | 330 |
Net income | 232 |  |  | 186 |  |  | 240 |  |  | 234 |  |  | 202 |  |  | 240 |
As of December 31: |  |  |  |  |  |  |  |  |  |  |
Current assets | 82 |  |  | 88 |  |  |  |  | 6 |  |  | 87 |  |  |
Non-current assets | 4,340 |  |  | 3,987 |  |  |  |  | 19 |  |  | 3,977 |  |  |
Current liabilities | 498 |  |  | 332 |  |  |  |  | 3 |  |  | 332 |  |  |
Non-current liabilities | 2,144 |  |  | 2,052 |  |  |  |  | 7 |  |  | 2,052 |  |  |
Cash Surrender Value of Life Insurance Policies | At December 31, the cash surrender value of these investments was as follows (in millions):
| Alliant Energy |  | IPL |  | WPL
| 2016 |  | 2015 |  | 2016 |  | 2015 |  | 2016 |  | 2015
Cash surrender value | $10.6 |  | $42.3 |  | $— |  | $18.9 |  | $5.8 |  | $6.4

X
- Definition Line items represent reporting 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 Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Article 12 -Section 12 -Sentence Column A + Details
Name: | invest_InvestmentLineItems
Namespace Prefix: | invest_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule Of Cash Surrender Value Of Life Insurance Policies [Table Text Block] + References No definition available. + Details
Name: | lnt_ScheduleOfCashSurrenderValueOfLifeInsurancePoliciesTableTextBlock
Namespace Prefix: | lnt_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Schedule of Summary Financial Information [Table Text Block] + References No definition available. + Details
Name: | lnt_ScheduleOfSummaryFinancialInformationTableTextBlock
Namespace Prefix: | lnt_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- Definition Tabular disclosure of equity method investments including, but not limited to, name of each investee or group of investments, percentage ownership, difference between recorded amount of an investment and the value of the underlying equity in the net assets, and summarized financial information. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 323 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571 + Details
Name: | us-gaap_EquityMethodInvestmentsTextBlock
Namespace Prefix: | us-gaap_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

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

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