Property, Plant and Equipment

12 Months Ended

Dec. 31, 2016

Property, Plant and Equipment [Line Items]

Property, Plant and Equipment

PROPERTY, PLANT AND EQUIPMENT

At December 31, details of property, plant and equipment on the balance sheets were as follows (in millions):

	Alliant Energy						IPL						WPL
	2016			2015			2016			2015			2016			2015
Utility:
Electric plant:
Generation in service		$5,866.9			$5,643.7			$2,916.8			$3,011.6			$2,950.1			$2,632.1
Distribution in service	4,739.2			4,489.9			2,589.3			2,447.9			2,149.9			2,042.0
Other in service	329.1			311.3			223.5			212.2			105.6			99.1
Anticipated to be retired early (a)	108.3			—			108.3			—			—			—
Total electric plant	11,043.5			10,444.9			5,837.9			5,671.7			5,205.6			4,773.2
Gas plant in service	1,107.6			1,018.3			556.7			513.6			550.9			504.7
Other plant in service	549.3			530.6			313.0			296.0			236.3			234.6
Accumulated depreciation	(4,135.7		)	(3,939.6		)	(2,258.3		)	(2,152.8		)	(1,877.4		)	(1,786.8		)
Net plant	8,564.7			8,054.2			4,449.3			4,328.5			4,115.4			3,725.7
Leased Sheboygan Falls Energy Facility, net (b)	—			—			—			—			52.4			58.6
Construction work in progress	1,226.8			897.5			968.1			578.2			258.7			319.3
Other, net	18.4			18.5			18.2			18.4			0.2			0.1
Total utility	9,809.9			8,970.2			5,435.6			4,925.1			4,426.7			4,103.7
Non-regulated and other:
Non-regulated Generation, net (c)	135.0			229.3			—			—			—			—
Corporate Services and other, net (d)	334.3			319.6			—			—			—			—
Total non-regulated and other	469.3			548.9			—			—			—			—
Total property, plant and equipment		$10,279.2			$9,519.1			$5,435.6			$4,925.1			$4,426.7			$4,103.7

(a) In 2016, IPL received approval from MISO to retire Sutherland Unit 3 and currently anticipates retiring this EGU by June 30, 2017. The recovery of the remaining net book value of this EGU is expected to be addressed in IPL’s next retail electric base rate case, which is currently expected to be filed in the second quarter of 2017.

(b) Less accumulated amortization of $71.4 million and $65.2 million for WPL as of December 31, 2016 and 2015, respectively. The Sheboygan Falls Energy Facility is eliminated from WPL upon consolidation and is included in the “Non-regulated Generation, net” line within Alliant Energy’s consolidated property, plant and equipment.

(c) Less accumulated depreciation of $46.5 million and $59.0 million for Alliant Energy as of December 31, 2016 and 2015, respectively.

(d) Less accumulated depreciation of $272.0 million and $252.9 million for Alliant Energy as of December 31, 2016 and 2015, respectively.

Utility -

Environmental Controls Project -

WPL’s Edgewater Unit 5 - Construction of a scrubber and baghouse at Edgewater Unit 5 began in 2014 and was completed in 2016, which resulted in a transfer of the capitalized project costs from “Construction work in progress” to “Electric plant - Generation in service” in the above table for Alliant Energy and WPL in 2016. As of December 31, 2016 and 2015, the capitalized project costs for the scrubber and baghouse consisted of capitalized expenditures of $225 million and CWIP of $190 million, and AFUDC of $12 million and $8 million, respectively, for the scrubber and baghouse. The scrubber and baghouse reduce SO2 and mercury emissions at the EGU and are expected to help meet requirements under CSAPR.

Natural Gas-Fired Generation Projects -

IPL’s Marshalltown Generating Station - IPL is currently constructing Marshalltown, an approximate 650 MW natural gas-fired combined-cycle EGU. Construction began in 2014 and is expected to be completed in April 2017. As of December 31, 2016 and 2015, Alliant Energy and IPL recorded capitalized expenditures for CWIP of $612 million and $453 million, and AFUDC of $68 million and $24 million, respectively, for Marshalltown in “Construction work in progress” in the above table for Alliant Energy and IPL.

WPL’s Riverside Expansion - WPL is currently constructing the Riverside expansion, an approximate 730 MW natural gas-fired combined-cycle EGU. Construction began in 2016 and is expected to be completed in early 2020. As of December 31, 2016 and 2015, Alliant Energy and WPL recorded capitalized expenditures for CWIP of $81 million and $2 million, and AFUDC of $2 million and $0, respectively, for the Riverside expansion in “Construction work in progress” in the above table for Alliant Energy and WPL. These capital expenditures exclude any potential impacts from the intent to exercise purchase options by certain WPL electric cooperatives for a partial ownership interest in the Riverside expansion.

Wind Generation -

IPL’s Expansion of Wind Generation - IPL currently plans to add wind generation to its resources portfolio. In 2016, IPL entered into a turbine supply agreement and made progress payments for a portion of the wind turbines in such agreement in order to qualify for the full level of production tax credits for this new wind generation. IPL anticipates placing certain of the additional wind generation in service in 2019 and 2020. As of December 31, 2016, Alliant Energy and IPL recorded capitalized expenditures for CWIP of $102 million and AFUDC of $1 million for this expansion of wind generation in “Construction work in progress” in the above table for Alliant Energy and IPL.

Sales of IPL’s Minnesota Electric and Natural Gas Distribution Assets - In 2015, IPL completed the sale of its Minnesota natural gas distribution assets (primarily related to property, plant and equipment) and received proceeds of $11 million and a promissory note of $2 million. In 2015, IPL completed the sale of its Minnesota electric distribution assets (primarily related to property, plant and equipment) to Southern Minnesota Energy Cooperative, a combined group of various neighboring electric cooperatives, and received proceeds of $129 million. The proceeds from the natural gas distribution assets were used for general corporate purposes and the proceeds from the electric distribution assets were used to reduce cash amounts received from IPL’s sales of accounts receivable program. The premium received over the book value of the property, plant and equipment sold was more than offset by a reduction in tax-related regulatory assets associated with the distribution assets. As a result, Alliant Energy and IPL recorded pre-tax charges of $11 million and $3 million for the Minnesota electric and natural gas distribution asset transactions, respectively, in “Other operation and maintenance” in their income statements in 2015.

The electric distribution asset sales agreement includes a wholesale power supply agreement between IPL and Southern Minnesota Energy Cooperative, which was approved by FERC in 2015 and became effective upon the sale of IPL’s Minnesota electric distribution assets. The wholesale power supply agreement contains a five-year termination notice, which may not be given until the fifth anniversary of the effective date of the agreement, resulting in a minimum term of 10 years. The agreement remains in effect indefinitely, unless notice to terminate is provided by either party. This wholesale power supply agreement includes standardized pricing mechanisms that are detailed in IPL’s current tariffs accepted by FERC through wholesale rate case proceedings. IPL’s current return on common equity authorized by FERC related to its wholesale electric rates is 10.97%. As a result of IPL’s requirement to supply electricity to Southern Minnesota Energy Cooperative under the wholesale power supply agreement, the sale of the electric distribution assets did not have a significant impact on IPL’s generation plans or operating results.

AFUDC - AFUDC represents costs to finance construction additions including a return on equity component and cost of debt component as required by regulatory accounting. The concurrent credit for the amount of AFUDC capitalized is recorded as “Allowance for funds used during construction” in the income statements. The amount of AFUDC generated by equity and debt components was as follows (in millions):

	Alliant Energy						IPL						WPL
	2016		2015		2014		2016		2015		2014		2016		2015		2014
Equity		$42.3		$24.4		$23.1		$35.2		$18.6		$17.1		$7.1		$5.8		$6.0
Debt	20.2		12.5		11.7		16.8		9.6		8.8		3.4		2.9		2.9
		$62.5		$36.9		$34.8		$52.0		$28.2		$25.9		$10.5		$8.7		$8.9

AFUDC related to various construction projects was recognized in the income statements as follows (in millions):

	2016		2015		2014
IPL:
Marshalltown		$43.8		$20.7		$3.7
Environmental controls - Ottumwa Unit 1	—		—		10.6
Other	8.2		7.5		11.6
	52.0		28.2		25.9
WPL:
Environmental controls - Edgewater Unit 5	4.3		5.1		2.7
Other	6.2		3.6		6.2
	10.5		8.7		8.9
Alliant Energy		$62.5		$36.9		$34.8

Non-regulated and Other - The non-regulated and other property, plant and equipment recorded on Alliant Energy’s balance sheets includes the following:

Non-regulated Generation -

Franklin County Wind Farm - The Franklin County wind farm was placed into service in 2012 and is depreciated using the straight-line method over a 30-year period. Based on an evaluation of the strategic options for the Franklin County wind farm performed in 2016, Alliant Energy concluded it was probable the Franklin County wind farm will be transferred to IPL. As a result, Alliant Energy performed an impairment analysis of such assets in 2016. The impairment analysis evaluated the value of the assets and a reasonable estimate of the amount of costs associated with the Franklin County wind farm that would be allowed for recovery for IPL’s electric rate-making purposes. Based on various analyses, including discounted cash flows projected from the Franklin County wind farm, recently executed PPAs associated with wind generating facilities located near the Franklin County wind farm, and the cost of new wind farms identified through IPL’s planned wind expansion, the value of the Franklin County wind farm assets was determined to be approximately $33 million, subject to working capital adjustments. Alliant Energy concluded such value represents a reasonable estimate of the amount IPL will be allowed for recovery for IPL’s electric rate-making purposes. As a result, in 2016, the carrying amount of the Franklin County wind farm was reduced to such value, resulting in non-cash, pre-tax asset valuation charges of $86 million (after-tax charges of $51 million, or $0.23 per share). In 2016, Alliant Energy recorded such charges as a reduction to “Non-regulated Generation, net” in the above table and charges to “Asset valuation charges for Franklin County wind farm” in its income statement.

In February 2017, FERC issued an order approving the transfer of the Franklin County wind farm from AEF to IPL. Alliant Energy and IPL currently expect to complete this transfer in 2017. The final amount to be recovered for IPL’s electric rate-making purposes is expected to be determined by the IUB as part of IPL’s retail electric rate case for the 2016 Test Year, currently anticipated to be filed in the second quarter of 2017, and therefore the final asset valuation charges are subject to change.

Sheboygan Falls - Sheboygan Falls was placed into service in 2005 and is depreciated using the straight-line method over a 35-year period. As of December 31, 2016, Alliant Energy recorded $95 million on its balance sheet related to Sheboygan Falls.

Corporate Services and Other - Property, plant and equipment related to Corporate Services includes a customer billing and information system for IPL and WPL and other computer software, and the corporate headquarters building located in Madison, Wisconsin. The customer billing and information system is amortized using the straight-line method over a 12-year period. The majority of the remaining software is amortized over a 5-year period. Property, plant and equipment related to Transportation includes a short-line railway in Iowa and a barge terminal on the Mississippi River. The Corporate Services and Other property, plant and equipment is depreciated using the straight-line method over periods ranging from 5 to 30 years.

IPL [Member]

Property, Plant and Equipment [Line Items]

Property, Plant and Equipment

PROPERTY, PLANT AND EQUIPMENT

At December 31, details of property, plant and equipment on the balance sheets were as follows (in millions):

	Alliant Energy						IPL						WPL
	2016			2015			2016			2015			2016			2015
Utility:
Electric plant:
Generation in service		$5,866.9			$5,643.7			$2,916.8			$3,011.6			$2,950.1			$2,632.1
Distribution in service	4,739.2			4,489.9			2,589.3			2,447.9			2,149.9			2,042.0
Other in service	329.1			311.3			223.5			212.2			105.6			99.1
Anticipated to be retired early (a)	108.3			—			108.3			—			—			—
Total electric plant	11,043.5			10,444.9			5,837.9			5,671.7			5,205.6			4,773.2
Gas plant in service	1,107.6			1,018.3			556.7			513.6			550.9			504.7
Other plant in service	549.3			530.6			313.0			296.0			236.3			234.6
Accumulated depreciation	(4,135.7		)	(3,939.6		)	(2,258.3		)	(2,152.8		)	(1,877.4		)	(1,786.8		)
Net plant	8,564.7			8,054.2			4,449.3			4,328.5			4,115.4			3,725.7
Leased Sheboygan Falls Energy Facility, net (b)	—			—			—			—			52.4			58.6
Construction work in progress	1,226.8			897.5			968.1			578.2			258.7			319.3
Other, net	18.4			18.5			18.2			18.4			0.2			0.1
Total utility	9,809.9			8,970.2			5,435.6			4,925.1			4,426.7			4,103.7
Non-regulated and other:
Non-regulated Generation, net (c)	135.0			229.3			—			—			—			—
Corporate Services and other, net (d)	334.3			319.6			—			—			—			—
Total non-regulated and other	469.3			548.9			—			—			—			—
Total property, plant and equipment		$10,279.2			$9,519.1			$5,435.6			$4,925.1			$4,426.7			$4,103.7

(a) In 2016, IPL received approval from MISO to retire Sutherland Unit 3 and currently anticipates retiring this EGU by June 30, 2017. The recovery of the remaining net book value of this EGU is expected to be addressed in IPL’s next retail electric base rate case, which is currently expected to be filed in the second quarter of 2017.

(b) Less accumulated amortization of $71.4 million and $65.2 million for WPL as of December 31, 2016 and 2015, respectively. The Sheboygan Falls Energy Facility is eliminated from WPL upon consolidation and is included in the “Non-regulated Generation, net” line within Alliant Energy’s consolidated property, plant and equipment.

(c) Less accumulated depreciation of $46.5 million and $59.0 million for Alliant Energy as of December 31, 2016 and 2015, respectively.

(d) Less accumulated depreciation of $272.0 million and $252.9 million for Alliant Energy as of December 31, 2016 and 2015, respectively.

Utility -

Environmental Controls Project -

WPL’s Edgewater Unit 5 - Construction of a scrubber and baghouse at Edgewater Unit 5 began in 2014 and was completed in 2016, which resulted in a transfer of the capitalized project costs from “Construction work in progress” to “Electric plant - Generation in service” in the above table for Alliant Energy and WPL in 2016. As of December 31, 2016 and 2015, the capitalized project costs for the scrubber and baghouse consisted of capitalized expenditures of $225 million and CWIP of $190 million, and AFUDC of $12 million and $8 million, respectively, for the scrubber and baghouse. The scrubber and baghouse reduce SO2 and mercury emissions at the EGU and are expected to help meet requirements under CSAPR.

Natural Gas-Fired Generation Projects -

IPL’s Marshalltown Generating Station - IPL is currently constructing Marshalltown, an approximate 650 MW natural gas-fired combined-cycle EGU. Construction began in 2014 and is expected to be completed in April 2017. As of December 31, 2016 and 2015, Alliant Energy and IPL recorded capitalized expenditures for CWIP of $612 million and $453 million, and AFUDC of $68 million and $24 million, respectively, for Marshalltown in “Construction work in progress” in the above table for Alliant Energy and IPL.

WPL’s Riverside Expansion - WPL is currently constructing the Riverside expansion, an approximate 730 MW natural gas-fired combined-cycle EGU. Construction began in 2016 and is expected to be completed in early 2020. As of December 31, 2016 and 2015, Alliant Energy and WPL recorded capitalized expenditures for CWIP of $81 million and $2 million, and AFUDC of $2 million and $0, respectively, for the Riverside expansion in “Construction work in progress” in the above table for Alliant Energy and WPL. These capital expenditures exclude any potential impacts from the intent to exercise purchase options by certain WPL electric cooperatives for a partial ownership interest in the Riverside expansion.

Wind Generation -

IPL’s Expansion of Wind Generation - IPL currently plans to add wind generation to its resources portfolio. In 2016, IPL entered into a turbine supply agreement and made progress payments for a portion of the wind turbines in such agreement in order to qualify for the full level of production tax credits for this new wind generation. IPL anticipates placing certain of the additional wind generation in service in 2019 and 2020. As of December 31, 2016, Alliant Energy and IPL recorded capitalized expenditures for CWIP of $102 million and AFUDC of $1 million for this expansion of wind generation in “Construction work in progress” in the above table for Alliant Energy and IPL.

Sales of IPL’s Minnesota Electric and Natural Gas Distribution Assets - In 2015, IPL completed the sale of its Minnesota natural gas distribution assets (primarily related to property, plant and equipment) and received proceeds of $11 million and a promissory note of $2 million. In 2015, IPL completed the sale of its Minnesota electric distribution assets (primarily related to property, plant and equipment) to Southern Minnesota Energy Cooperative, a combined group of various neighboring electric cooperatives, and received proceeds of $129 million. The proceeds from the natural gas distribution assets were used for general corporate purposes and the proceeds from the electric distribution assets were used to reduce cash amounts received from IPL’s sales of accounts receivable program. The premium received over the book value of the property, plant and equipment sold was more than offset by a reduction in tax-related regulatory assets associated with the distribution assets. As a result, Alliant Energy and IPL recorded pre-tax charges of $11 million and $3 million for the Minnesota electric and natural gas distribution asset transactions, respectively, in “Other operation and maintenance” in their income statements in 2015.

The electric distribution asset sales agreement includes a wholesale power supply agreement between IPL and Southern Minnesota Energy Cooperative, which was approved by FERC in 2015 and became effective upon the sale of IPL’s Minnesota electric distribution assets. The wholesale power supply agreement contains a five-year termination notice, which may not be given until the fifth anniversary of the effective date of the agreement, resulting in a minimum term of 10 years. The agreement remains in effect indefinitely, unless notice to terminate is provided by either party. This wholesale power supply agreement includes standardized pricing mechanisms that are detailed in IPL’s current tariffs accepted by FERC through wholesale rate case proceedings. IPL’s current return on common equity authorized by FERC related to its wholesale electric rates is 10.97%. As a result of IPL’s requirement to supply electricity to Southern Minnesota Energy Cooperative under the wholesale power supply agreement, the sale of the electric distribution assets did not have a significant impact on IPL’s generation plans or operating results.

AFUDC - AFUDC represents costs to finance construction additions including a return on equity component and cost of debt component as required by regulatory accounting. The concurrent credit for the amount of AFUDC capitalized is recorded as “Allowance for funds used during construction” in the income statements. The amount of AFUDC generated by equity and debt components was as follows (in millions):

	Alliant Energy						IPL						WPL
	2016		2015		2014		2016		2015		2014		2016		2015		2014
Equity		$42.3		$24.4		$23.1		$35.2		$18.6		$17.1		$7.1		$5.8		$6.0
Debt	20.2		12.5		11.7		16.8		9.6		8.8		3.4		2.9		2.9
		$62.5		$36.9		$34.8		$52.0		$28.2		$25.9		$10.5		$8.7		$8.9

AFUDC related to various construction projects was recognized in the income statements as follows (in millions):

	2016		2015		2014
IPL:
Marshalltown		$43.8		$20.7		$3.7
Environmental controls - Ottumwa Unit 1	—		—		10.6
Other	8.2		7.5		11.6
	52.0		28.2		25.9
WPL:
Environmental controls - Edgewater Unit 5	4.3		5.1		2.7
Other	6.2		3.6		6.2
	10.5		8.7		8.9
Alliant Energy		$62.5		$36.9		$34.8

WPL [Member]

Property, Plant and Equipment [Line Items]

Property, Plant and Equipment

PROPERTY, PLANT AND EQUIPMENT

At December 31, details of property, plant and equipment on the balance sheets were as follows (in millions):

	Alliant Energy						IPL						WPL
	2016			2015			2016			2015			2016			2015
Utility:
Electric plant:
Generation in service		$5,866.9			$5,643.7			$2,916.8			$3,011.6			$2,950.1			$2,632.1
Distribution in service	4,739.2			4,489.9			2,589.3			2,447.9			2,149.9			2,042.0
Other in service	329.1			311.3			223.5			212.2			105.6			99.1
Anticipated to be retired early (a)	108.3			—			108.3			—			—			—
Total electric plant	11,043.5			10,444.9			5,837.9			5,671.7			5,205.6			4,773.2
Gas plant in service	1,107.6			1,018.3			556.7			513.6			550.9			504.7
Other plant in service	549.3			530.6			313.0			296.0			236.3			234.6
Accumulated depreciation	(4,135.7		)	(3,939.6		)	(2,258.3		)	(2,152.8		)	(1,877.4		)	(1,786.8		)
Net plant	8,564.7			8,054.2			4,449.3			4,328.5			4,115.4			3,725.7
Leased Sheboygan Falls Energy Facility, net (b)	—			—			—			—			52.4			58.6
Construction work in progress	1,226.8			897.5			968.1			578.2			258.7			319.3
Other, net	18.4			18.5			18.2			18.4			0.2			0.1
Total utility	9,809.9			8,970.2			5,435.6			4,925.1			4,426.7			4,103.7
Non-regulated and other:
Non-regulated Generation, net (c)	135.0			229.3			—			—			—			—
Corporate Services and other, net (d)	334.3			319.6			—			—			—			—
Total non-regulated and other	469.3			548.9			—			—			—			—
Total property, plant and equipment		$10,279.2			$9,519.1			$5,435.6			$4,925.1			$4,426.7			$4,103.7

(a) In 2016, IPL received approval from MISO to retire Sutherland Unit 3 and currently anticipates retiring this EGU by June 30, 2017. The recovery of the remaining net book value of this EGU is expected to be addressed in IPL’s next retail electric base rate case, which is currently expected to be filed in the second quarter of 2017.

(b) Less accumulated amortization of $71.4 million and $65.2 million for WPL as of December 31, 2016 and 2015, respectively. The Sheboygan Falls Energy Facility is eliminated from WPL upon consolidation and is included in the “Non-regulated Generation, net” line within Alliant Energy’s consolidated property, plant and equipment.

(c) Less accumulated depreciation of $46.5 million and $59.0 million for Alliant Energy as of December 31, 2016 and 2015, respectively.

(d) Less accumulated depreciation of $272.0 million and $252.9 million for Alliant Energy as of December 31, 2016 and 2015, respectively.

Utility -

Environmental Controls Project -

WPL’s Edgewater Unit 5 - Construction of a scrubber and baghouse at Edgewater Unit 5 began in 2014 and was completed in 2016, which resulted in a transfer of the capitalized project costs from “Construction work in progress” to “Electric plant - Generation in service” in the above table for Alliant Energy and WPL in 2016. As of December 31, 2016 and 2015, the capitalized project costs for the scrubber and baghouse consisted of capitalized expenditures of $225 million and CWIP of $190 million, and AFUDC of $12 million and $8 million, respectively, for the scrubber and baghouse. The scrubber and baghouse reduce SO2 and mercury emissions at the EGU and are expected to help meet requirements under CSAPR.

Natural Gas-Fired Generation Projects -

IPL’s Marshalltown Generating Station - IPL is currently constructing Marshalltown, an approximate 650 MW natural gas-fired combined-cycle EGU. Construction began in 2014 and is expected to be completed in April 2017. As of December 31, 2016 and 2015, Alliant Energy and IPL recorded capitalized expenditures for CWIP of $612 million and $453 million, and AFUDC of $68 million and $24 million, respectively, for Marshalltown in “Construction work in progress” in the above table for Alliant Energy and IPL.

WPL’s Riverside Expansion - WPL is currently constructing the Riverside expansion, an approximate 730 MW natural gas-fired combined-cycle EGU. Construction began in 2016 and is expected to be completed in early 2020. As of December 31, 2016 and 2015, Alliant Energy and WPL recorded capitalized expenditures for CWIP of $81 million and $2 million, and AFUDC of $2 million and $0, respectively, for the Riverside expansion in “Construction work in progress” in the above table for Alliant Energy and WPL. These capital expenditures exclude any potential impacts from the intent to exercise purchase options by certain WPL electric cooperatives for a partial ownership interest in the Riverside expansion.

Wind Generation -

IPL’s Expansion of Wind Generation - IPL currently plans to add wind generation to its resources portfolio. In 2016, IPL entered into a turbine supply agreement and made progress payments for a portion of the wind turbines in such agreement in order to qualify for the full level of production tax credits for this new wind generation. IPL anticipates placing certain of the additional wind generation in service in 2019 and 2020. As of December 31, 2016, Alliant Energy and IPL recorded capitalized expenditures for CWIP of $102 million and AFUDC of $1 million for this expansion of wind generation in “Construction work in progress” in the above table for Alliant Energy and IPL.

Sales of IPL’s Minnesota Electric and Natural Gas Distribution Assets - In 2015, IPL completed the sale of its Minnesota natural gas distribution assets (primarily related to property, plant and equipment) and received proceeds of $11 million and a promissory note of $2 million. In 2015, IPL completed the sale of its Minnesota electric distribution assets (primarily related to property, plant and equipment) to Southern Minnesota Energy Cooperative, a combined group of various neighboring electric cooperatives, and received proceeds of $129 million. The proceeds from the natural gas distribution assets were used for general corporate purposes and the proceeds from the electric distribution assets were used to reduce cash amounts received from IPL’s sales of accounts receivable program. The premium received over the book value of the property, plant and equipment sold was more than offset by a reduction in tax-related regulatory assets associated with the distribution assets. As a result, Alliant Energy and IPL recorded pre-tax charges of $11 million and $3 million for the Minnesota electric and natural gas distribution asset transactions, respectively, in “Other operation and maintenance” in their income statements in 2015.

The electric distribution asset sales agreement includes a wholesale power supply agreement between IPL and Southern Minnesota Energy Cooperative, which was approved by FERC in 2015 and became effective upon the sale of IPL’s Minnesota electric distribution assets. The wholesale power supply agreement contains a five-year termination notice, which may not be given until the fifth anniversary of the effective date of the agreement, resulting in a minimum term of 10 years. The agreement remains in effect indefinitely, unless notice to terminate is provided by either party. This wholesale power supply agreement includes standardized pricing mechanisms that are detailed in IPL’s current tariffs accepted by FERC through wholesale rate case proceedings. IPL’s current return on common equity authorized by FERC related to its wholesale electric rates is 10.97%. As a result of IPL’s requirement to supply electricity to Southern Minnesota Energy Cooperative under the wholesale power supply agreement, the sale of the electric distribution assets did not have a significant impact on IPL’s generation plans or operating results.

AFUDC - AFUDC represents costs to finance construction additions including a return on equity component and cost of debt component as required by regulatory accounting. The concurrent credit for the amount of AFUDC capitalized is recorded as “Allowance for funds used during construction” in the income statements. The amount of AFUDC generated by equity and debt components was as follows (in millions):

	Alliant Energy						IPL						WPL
	2016		2015		2014		2016		2015		2014		2016		2015		2014
Equity		$42.3		$24.4		$23.1		$35.2		$18.6		$17.1		$7.1		$5.8		$6.0
Debt	20.2		12.5		11.7		16.8		9.6		8.8		3.4		2.9		2.9
		$62.5		$36.9		$34.8		$52.0		$28.2		$25.9		$10.5		$8.7		$8.9

AFUDC related to various construction projects was recognized in the income statements as follows (in millions):

	2016		2015		2014
IPL:
Marshalltown		$43.8		$20.7		$3.7
Environmental controls - Ottumwa Unit 1	—		—		10.6
Other	8.2		7.5		11.6
	52.0		28.2		25.9
WPL:
Environmental controls - Edgewater Unit 5	4.3		5.1		2.7
Other	6.2		3.6		6.2
	10.5		8.7		8.9
Alliant Energy		$62.5		$36.9		$34.8