Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2018

Property, Plant and Equipment [Line Items]

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
	2018			2017			2018			2017			2018			2017
Utility:
Electric plant:
Generation in service		$6,800.6			$6,655.3			$3,610.4			$3,715.9			$3,190.2			$2,939.4
Distribution in service	5,452.2			5,123.5			3,023.7			2,820.9			2,428.5			2,302.6
Other in service	410.8			425.1			260.4			282.3			150.4			142.8
Anticipated to be retired early (a)	—			93.0			—			—			—			93.0
Total electric plant	12,663.6			12,296.9			6,894.5			6,819.1			5,769.1			5,477.8
Gas plant in service	1,387.6			1,244.0			763.1			654.8			624.5			589.2
Other plant in service	513.2			571.9			322.4			333.4			190.8			238.5
Accumulated depreciation	(4,314.6		)	(4,283.1		)	(2,294.7		)	(2,311.0		)	(2,019.9		)	(1,972.1		)
Net plant	10,249.8			9,829.7			5,685.3			5,496.3			4,564.5			4,333.4
Leased Sheboygan Falls Energy Facility, net (b)	—			—			—			—			38.1			46.2
Construction work in progress	1,774.8			962.2			1,091.2			424.4			683.6			537.8
Other, net	6.1			6.0			5.0			5.5			1.1			0.5
Total utility	12,030.7			10,797.9			6,781.5			5,926.2			5,287.3			4,917.9
Non-utility and other:
Non-utility Generation, net (c)	86.9			90.9			—			—			—			—
Corporate Services and other, net (d)	344.8			345.7			—			—			—			—
Total non-utility and other	431.7			436.6			—			—			—			—
Total property, plant and equipment		$12,462.4			$11,234.5			$6,781.5			$5,926.2			$5,287.3			$4,917.9

(a) In 2018, WPL retired Edgewater Unit 4 and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset on Alliant Energy’s and WPL’s balance sheets.

(b) Less accumulated amortization of $82.8 million and $77.6 million for WPL as of December 31, 2018 and 2017, respectively. The Sheboygan Falls Energy Facility is eliminated from WPL upon consolidation and is included in the “Non-utility Generation, net” line within Alliant Energy’s consolidated property, plant and equipment.

(c) Less accumulated depreciation of $54.5 million and $50.5 million for Alliant Energy as of December 31, 2018 and 2017, respectively.

(d) Less accumulated depreciation of $167.5 million and $285.6 million for Alliant Energy as of December 31, 2018 and 2017, respectively.

Allowance For Funds Used During Construction

The amount of AFUDC generated by equity and debt components was as follows (in millions):

	Alliant Energy						IPL						WPL
	2018		2017		2016		2018		2017		2016		2018		2017		2016
Equity		$51.4		$33.6		$42.3		$28.6		$21.1		$35.2		$22.8		$12.5		$7.1
Debt	24.2		16.1		20.2		13.6		10.3		16.8		10.6		5.8		3.4
		$75.6		$49.7		$62.5		$42.2		$31.4		$52.0		$33.4		$18.3		$10.5

IPL [Member]

Property, Plant and Equipment [Line Items]

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
	2018			2017			2018			2017			2018			2017
Utility:
Electric plant:
Generation in service		$6,800.6			$6,655.3			$3,610.4			$3,715.9			$3,190.2			$2,939.4
Distribution in service	5,452.2			5,123.5			3,023.7			2,820.9			2,428.5			2,302.6
Other in service	410.8			425.1			260.4			282.3			150.4			142.8
Anticipated to be retired early (a)	—			93.0			—			—			—			93.0
Total electric plant	12,663.6			12,296.9			6,894.5			6,819.1			5,769.1			5,477.8
Gas plant in service	1,387.6			1,244.0			763.1			654.8			624.5			589.2
Other plant in service	513.2			571.9			322.4			333.4			190.8			238.5
Accumulated depreciation	(4,314.6		)	(4,283.1		)	(2,294.7		)	(2,311.0		)	(2,019.9		)	(1,972.1		)
Net plant	10,249.8			9,829.7			5,685.3			5,496.3			4,564.5			4,333.4
Leased Sheboygan Falls Energy Facility, net (b)	—			—			—			—			38.1			46.2
Construction work in progress	1,774.8			962.2			1,091.2			424.4			683.6			537.8
Other, net	6.1			6.0			5.0			5.5			1.1			0.5
Total utility	12,030.7			10,797.9			6,781.5			5,926.2			5,287.3			4,917.9
Non-utility and other:
Non-utility Generation, net (c)	86.9			90.9			—			—			—			—
Corporate Services and other, net (d)	344.8			345.7			—			—			—			—
Total non-utility and other	431.7			436.6			—			—			—			—
Total property, plant and equipment		$12,462.4			$11,234.5			$6,781.5			$5,926.2			$5,287.3			$4,917.9

(a) In 2018, WPL retired Edgewater Unit 4 and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset on Alliant Energy’s and WPL’s balance sheets.

(b) Less accumulated amortization of $82.8 million and $77.6 million for WPL as of December 31, 2018 and 2017, respectively. The Sheboygan Falls Energy Facility is eliminated from WPL upon consolidation and is included in the “Non-utility Generation, net” line within Alliant Energy’s consolidated property, plant and equipment.

(c) Less accumulated depreciation of $54.5 million and $50.5 million for Alliant Energy as of December 31, 2018 and 2017, respectively.

(d) Less accumulated depreciation of $167.5 million and $285.6 million for Alliant Energy as of December 31, 2018 and 2017, respectively.

Allowance For Funds Used During Construction

The amount of AFUDC generated by equity and debt components was as follows (in millions):

	Alliant Energy						IPL						WPL
	2018		2017		2016		2018		2017		2016		2018		2017		2016
Equity		$51.4		$33.6		$42.3		$28.6		$21.1		$35.2		$22.8		$12.5		$7.1
Debt	24.2		16.1		20.2		13.6		10.3		16.8		10.6		5.8		3.4
		$75.6		$49.7		$62.5		$42.2		$31.4		$52.0		$33.4		$18.3		$10.5

WPL [Member]

Property, Plant and Equipment [Line Items]

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
	2018			2017			2018			2017			2018			2017
Utility:
Electric plant:
Generation in service		$6,800.6			$6,655.3			$3,610.4			$3,715.9			$3,190.2			$2,939.4
Distribution in service	5,452.2			5,123.5			3,023.7			2,820.9			2,428.5			2,302.6
Other in service	410.8			425.1			260.4			282.3			150.4			142.8
Anticipated to be retired early (a)	—			93.0			—			—			—			93.0
Total electric plant	12,663.6			12,296.9			6,894.5			6,819.1			5,769.1			5,477.8
Gas plant in service	1,387.6			1,244.0			763.1			654.8			624.5			589.2
Other plant in service	513.2			571.9			322.4			333.4			190.8			238.5
Accumulated depreciation	(4,314.6		)	(4,283.1		)	(2,294.7		)	(2,311.0		)	(2,019.9		)	(1,972.1		)
Net plant	10,249.8			9,829.7			5,685.3			5,496.3			4,564.5			4,333.4
Leased Sheboygan Falls Energy Facility, net (b)	—			—			—			—			38.1			46.2
Construction work in progress	1,774.8			962.2			1,091.2			424.4			683.6			537.8
Other, net	6.1			6.0			5.0			5.5			1.1			0.5
Total utility	12,030.7			10,797.9			6,781.5			5,926.2			5,287.3			4,917.9
Non-utility and other:
Non-utility Generation, net (c)	86.9			90.9			—			—			—			—
Corporate Services and other, net (d)	344.8			345.7			—			—			—			—
Total non-utility and other	431.7			436.6			—			—			—			—
Total property, plant and equipment		$12,462.4			$11,234.5			$6,781.5			$5,926.2			$5,287.3			$4,917.9

(a) In 2018, WPL retired Edgewater Unit 4 and reclassified the remaining net book value of this EGU from property, plant and equipment to a regulatory asset on Alliant Energy’s and WPL’s balance sheets.

(b) Less accumulated amortization of $82.8 million and $77.6 million for WPL as of December 31, 2018 and 2017, respectively. The Sheboygan Falls Energy Facility is eliminated from WPL upon consolidation and is included in the “Non-utility Generation, net” line within Alliant Energy’s consolidated property, plant and equipment.

(c) Less accumulated depreciation of $54.5 million and $50.5 million for Alliant Energy as of December 31, 2018 and 2017, respectively.

(d) Less accumulated depreciation of $167.5 million and $285.6 million for Alliant Energy as of December 31, 2018 and 2017, respectively.

Allowance For Funds Used During Construction

The amount of AFUDC generated by equity and debt components was as follows (in millions):

	Alliant Energy						IPL						WPL
	2018		2017		2016		2018		2017		2016		2018		2017		2016
Equity		$51.4		$33.6		$42.3		$28.6		$21.1		$35.2		$22.8		$12.5		$7.1
Debt	24.2		16.1		20.2		13.6		10.3		16.8		10.6		5.8		3.4
		$75.6		$49.7		$62.5		$42.2		$31.4		$52.0		$33.4		$18.3		$10.5

Forward Wind Energy Center [Member]

Property, Plant and Equipment [Line Items]

Assets Purchased and Liabilities Assumed

As of the closing date, the estimated fair value of the assets purchased and the liabilities assumed by WPL were as follows (in millions):

Property, plant and equipment, net		$81
Liabilities	7
Net assets acquired		$74

Forward Wind Energy Center [Member] | WPL [Member]

Property, Plant and Equipment [Line Items]

Assets Purchased and Liabilities Assumed

As of the closing date, the estimated fair value of the assets purchased and the liabilities assumed by WPL were as follows (in millions):

Property, plant and equipment, net		$81
Liabilities	7
Net assets acquired		$74

Franklin County Wind Farm [Member]

Property, Plant and Equipment [Line Items]

Assets Purchased and Liabilities Assumed

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

Franklin County Wind Farm [Member] | IPL [Member]

Property, Plant and Equipment [Line Items]

Assets Purchased and Liabilities Assumed

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