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Investments | 3 Months Ended
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Mar. 31, 2018
Schedule of Investments [Line Items] |
Investments | INVESTMENTS Unconsolidated Equity Investments - Alliant Energy’s equity (income) loss from unconsolidated investments accounted for under the equity method of accounting for the three months ended March 31 was as follows (in millions):
| 2018 |  | 2017
ATC Holdings |  | ($8.7 | ) |  |  | ($11.5 | )
Non-utility wind farm in Oklahoma | (12.1 | ) |  | — |
Other | (0.5 | ) |  | — |
|  | ($21.3 | ) |  |  | ($11.5 | )
Non-utility Wind Farm in Oklahoma - Alliant Energy’s interest in a non-utility wind farm in Oklahoma commenced in July 2017. As a result, there was no corresponding equity income recognized in the first quarter of 2017. The equity income recognized in the first quarter of 2018 was primarily related to the impacts of Tax Reform. The liquidation method utilized to recognize Alliant Energy’s share of the wind farm’s earnings includes utilizing the federal income tax rate in effect as of the end of the measurement period. The lower federal income tax rate effective as of January 1, 2018 resulted in an acceleration of earnings attributable to Alliant Energy’s interest in the Oklahoma wind farm. This increase in earnings is expected to reverse over time.

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- 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=50485924&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=50485924&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=50485924&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=50485924&loc=d3e611133-123010 + Details
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