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Property, Plant and Equipment | 9 Months Ended
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Sep. 30, 2017
Property, Plant and Equipment [Line Items] |
Property, Plant and Equipment | PROPERTY, PLANT AND EQUIPMENT Utility - Natural Gas-Fired Generation Projects - IPL’s Marshalltown Generating Station - IPL’s construction of Marshalltown, an approximate 660 MW natural gas-fired combined-cycle EGU, was completed and the EGU was placed into service in April 2017. As of September 30, 2017, Alliant Energy and IPL recorded total project costs of $643 million and AFUDC of $81 million for Marshalltown in “Property, plant and equipment, net” on their balance sheets. WPL’s West Riverside Energy Center - WPL is currently constructing West Riverside, an approximate 730 MW natural gas-fired combined-cycle EGU. Construction began in 2016 and is currently expected to be completed by early 2020. As of September 30, 2017, Alliant Energy and WPL recorded capitalized expenditures for construction work in progress of $278 million and AFUDC of $9 million for West Riverside in “Property, plant and equipment, net” on their balance sheets. These capital expenditures do not yet reflect any potential impacts from the exercise of purchase options by certain WPL electric cooperatives for a partial ownership interest in West Riverside. Wind Generation - IPL’s Expansion of Wind Generation - IPL currently plans to add up to 1,000 MW of new wind projects to its existing generation portfolio. These wind projects are expected to be placed into service in 2019 and 2020. As of September 30, 2017, Alliant Energy and IPL recorded capitalized expenditures for construction work in progress of $184 million and AFUDC of $7 million for this expansion of wind generation in “Property, plant and equipment, net” on their balance sheets. Franklin County Wind Farm - Based on an evaluation of the strategic options for the Franklin County wind farm performed in the third quarter of 2016, Alliant Energy concluded, as of September 30, 2016, it was probable the Franklin County wind farm would be transferred to IPL. As a result, Alliant Energy performed an impairment analysis of such assets and recorded non-cash, pre-tax asset valuation charges of $86 million (after-tax charges of $51 million, or $0.23 per share) in the third quarter of 2016. Alliant Energy recorded such charges as a reduction to property, plant and equipment on its balance sheet in 2016 and charges to “Asset valuation charges for Franklin County wind farm” in its income statements for the three and nine months ended September 30, 2016. The proposed settlement for IPL’s retail electric rate review (2016 Test Year) included recovery of the transfer price for the Franklin County wind farm. In April 2017, the Franklin County wind farm was transferred from AEF to IPL as approved by a February 2017 FERC order. IPL’s purchase price, including certain transaction-related costs, was $32 million. As of the closing date, the estimated fair values of the assets purchased and liabilities assumed by IPL were as follows (in millions):
Electric plant in service |  | $40 |
Current assets | 2 |
Total assets acquired | 42 |
Other liabilities | 10 |
Net assets acquired |  | $32 |
WPL’s Proposed Acquisition of Forward Wind Energy Center - In October 2017, WPL entered into definitive agreements to acquire the assets of the Forward Wind Energy Center (FWEC), which is a 129 MW wind farm located in Wisconsin. WPL currently expects to acquire 55 MW of FWEC for approximately $74 million. WPL currently expects to file for approval from the PSCW and FERC in the fourth quarter of 2017, with decisions expected by the second quarter of 2018. Retirement of IPL’s Sutherland Units 1 and 3 - In June 2017, IPL retired Sutherland Units 1 and 3 and reclassified the remaining net book value of these EGUs from property, plant and equipment to a regulatory asset on Alliant Energy’s and IPL’s balance sheets. Refer to Note 2 for further discussion.
IPL [Member] |
Property, Plant and Equipment [Line Items] |
Property, Plant and Equipment | PROPERTY, PLANT AND EQUIPMENT Utility - Natural Gas-Fired Generation Projects - IPL’s Marshalltown Generating Station - IPL’s construction of Marshalltown, an approximate 660 MW natural gas-fired combined-cycle EGU, was completed and the EGU was placed into service in April 2017. As of September 30, 2017, Alliant Energy and IPL recorded total project costs of $643 million and AFUDC of $81 million for Marshalltown in “Property, plant and equipment, net” on their balance sheets. WPL’s West Riverside Energy Center - WPL is currently constructing West Riverside, an approximate 730 MW natural gas-fired combined-cycle EGU. Construction began in 2016 and is currently expected to be completed by early 2020. As of September 30, 2017, Alliant Energy and WPL recorded capitalized expenditures for construction work in progress of $278 million and AFUDC of $9 million for West Riverside in “Property, plant and equipment, net” on their balance sheets. These capital expenditures do not yet reflect any potential impacts from the exercise of purchase options by certain WPL electric cooperatives for a partial ownership interest in West Riverside. Wind Generation - IPL’s Expansion of Wind Generation - IPL currently plans to add up to 1,000 MW of new wind projects to its existing generation portfolio. These wind projects are expected to be placed into service in 2019 and 2020. As of September 30, 2017, Alliant Energy and IPL recorded capitalized expenditures for construction work in progress of $184 million and AFUDC of $7 million for this expansion of wind generation in “Property, plant and equipment, net” on their balance sheets. Franklin County Wind Farm - Based on an evaluation of the strategic options for the Franklin County wind farm performed in the third quarter of 2016, Alliant Energy concluded, as of September 30, 2016, it was probable the Franklin County wind farm would be transferred to IPL. As a result, Alliant Energy performed an impairment analysis of such assets and recorded non-cash, pre-tax asset valuation charges of $86 million (after-tax charges of $51 million, or $0.23 per share) in the third quarter of 2016. Alliant Energy recorded such charges as a reduction to property, plant and equipment on its balance sheet in 2016 and charges to “Asset valuation charges for Franklin County wind farm” in its income statements for the three and nine months ended September 30, 2016. The proposed settlement for IPL’s retail electric rate review (2016 Test Year) included recovery of the transfer price for the Franklin County wind farm. In April 2017, the Franklin County wind farm was transferred from AEF to IPL as approved by a February 2017 FERC order. IPL’s purchase price, including certain transaction-related costs, was $32 million. As of the closing date, the estimated fair values of the assets purchased and liabilities assumed by IPL were as follows (in millions):
Electric plant in service |  | $40 |
Current assets | 2 |
Total assets acquired | 42 |
Other liabilities | 10 |
Net assets acquired |  | $32 |
WPL’s Proposed Acquisition of Forward Wind Energy Center - In October 2017, WPL entered into definitive agreements to acquire the assets of the Forward Wind Energy Center (FWEC), which is a 129 MW wind farm located in Wisconsin. WPL currently expects to acquire 55 MW of FWEC for approximately $74 million. WPL currently expects to file for approval from the PSCW and FERC in the fourth quarter of 2017, with decisions expected by the second quarter of 2018. Retirement of IPL’s Sutherland Units 1 and 3 - In June 2017, IPL retired Sutherland Units 1 and 3 and reclassified the remaining net book value of these EGUs from property, plant and equipment to a regulatory asset on Alliant Energy’s and IPL’s balance sheets. Refer to Note 2 for further discussion.
WPL [Member] |
Property, Plant and Equipment [Line Items] |
Property, Plant and Equipment | PROPERTY, PLANT AND EQUIPMENT Utility - Natural Gas-Fired Generation Projects - IPL’s Marshalltown Generating Station - IPL’s construction of Marshalltown, an approximate 660 MW natural gas-fired combined-cycle EGU, was completed and the EGU was placed into service in April 2017. As of September 30, 2017, Alliant Energy and IPL recorded total project costs of $643 million and AFUDC of $81 million for Marshalltown in “Property, plant and equipment, net” on their balance sheets. WPL’s West Riverside Energy Center - WPL is currently constructing West Riverside, an approximate 730 MW natural gas-fired combined-cycle EGU. Construction began in 2016 and is currently expected to be completed by early 2020. As of September 30, 2017, Alliant Energy and WPL recorded capitalized expenditures for construction work in progress of $278 million and AFUDC of $9 million for West Riverside in “Property, plant and equipment, net” on their balance sheets. These capital expenditures do not yet reflect any potential impacts from the exercise of purchase options by certain WPL electric cooperatives for a partial ownership interest in West Riverside. Wind Generation - IPL’s Expansion of Wind Generation - IPL currently plans to add up to 1,000 MW of new wind projects to its existing generation portfolio. These wind projects are expected to be placed into service in 2019 and 2020. As of September 30, 2017, Alliant Energy and IPL recorded capitalized expenditures for construction work in progress of $184 million and AFUDC of $7 million for this expansion of wind generation in “Property, plant and equipment, net” on their balance sheets. Franklin County Wind Farm - Based on an evaluation of the strategic options for the Franklin County wind farm performed in the third quarter of 2016, Alliant Energy concluded, as of September 30, 2016, it was probable the Franklin County wind farm would be transferred to IPL. As a result, Alliant Energy performed an impairment analysis of such assets and recorded non-cash, pre-tax asset valuation charges of $86 million (after-tax charges of $51 million, or $0.23 per share) in the third quarter of 2016. Alliant Energy recorded such charges as a reduction to property, plant and equipment on its balance sheet in 2016 and charges to “Asset valuation charges for Franklin County wind farm” in its income statements for the three and nine months ended September 30, 2016. The proposed settlement for IPL’s retail electric rate review (2016 Test Year) included recovery of the transfer price for the Franklin County wind farm. In April 2017, the Franklin County wind farm was transferred from AEF to IPL as approved by a February 2017 FERC order. IPL’s purchase price, including certain transaction-related costs, was $32 million. As of the closing date, the estimated fair values of the assets purchased and liabilities assumed by IPL were as follows (in millions):
Electric plant in service |  | $40 |
Current assets | 2 |
Total assets acquired | 42 |
Other liabilities | 10 |
Net assets acquired |  | $32 |
WPL’s Proposed Acquisition of Forward Wind Energy Center - In October 2017, WPL entered into definitive agreements to acquire the assets of the Forward Wind Energy Center (FWEC), which is a 129 MW wind farm located in Wisconsin. WPL currently expects to acquire 55 MW of FWEC for approximately $74 million. WPL currently expects to file for approval from the PSCW and FERC in the fourth quarter of 2017, with decisions expected by the second quarter of 2018.

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- Definition The entire disclosure for long-lived, physical assets used in the normal conduct of business and not intended for resale. Includes, but is not limited to, accounting policies and methodology, roll forwards, depreciation, depletion and amortization expense, including composite depreciation, accumulated depreciation, depletion and amortization expense, useful lives and method used, income statement disclosures, assets held for sale and public utility disclosures. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 210 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.5-02.13-14) -URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 205 -SubTopic 20 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=64827811&loc=d3e1361-107760 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 2 -URI http://asc.fasb.org/extlink&oid=64862545&loc=d3e2921-110230 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 360 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6391035&loc=d3e2868-110229 + Details
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