Property, Plant and Equipment (Tables)

12 Months Ended

Dec. 31, 2015

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
	2015			2014			2015			2014			2015			2014
Utility:
Electric plant:
In service:
Generation		$5,643.7			$5,463.0			$3,011.6			$2,872.4			$2,632.1			$2,590.6
Distribution	4,489.9			4,435.4			2,447.9			2,471.7			2,042.0			1,963.7
Other	311.3			309.1			212.2			215.5			99.1			93.6
Anticipated to be retired early (a)	—			157.6			—			—			—			157.6
Total electric plant	10,444.9			10,365.1			5,671.7			5,559.6			4,773.2			4,805.5
Gas plant in service	1,018.3			946.2			513.6			474.0			504.7			472.2
Other plant in service	530.6			539.3			296.0			298.8			234.6			240.5
Accumulated depreciation (a)	(3,939.6		)	(3,923.1		)	(2,152.8		)	(2,124.5		)	(1,786.8		)	(1,798.6		)
Net plant	8,054.2			7,927.5			4,328.5			4,207.9			3,725.7			3,719.6
Leased Sheboygan Falls Energy Facility, net (b)	—			—			—			—			58.6			64.7
Construction work in progress	897.5			479.1			578.2			325.0			319.3			154.1
Other, net	18.5			22.3			18.4			21.8			0.1			0.5
Total utility	8,970.2			8,428.9			4,925.1			4,554.7			4,103.7			3,938.9
Non-regulated and other:
Non-regulated Generation, net (c)	229.3			240.1			—			—			—			—
Corporate Services and other, net (d)	319.6			269.4			—			—			—			—
Total non-regulated and other	548.9			509.5			—			—			—			—
Total property, plant and equipment		$9,519.1			$8,938.4			$4,925.1			$4,554.7			$4,103.7			$3,938.9

(a) In December 2015, WPL retired Nelson Dewey Units 1 and 2 and Edgewater Unit 3 and transferred the remaining net book value from property, plant and equipment to regulatory assets pursuant to orders from the PSCW and FERC. Refer to Note 2 for discussion of the recovery of the remaining net book value of these EGUs.

(b) Less accumulated amortization of $65.2 million and $59.1 million for WPL as of December 31, 2015 and 2014, respectively.

(c) Less accumulated depreciation of $59.0 million and $49.5 million for Alliant Energy as of December 31, 2015 and 2014, respectively.

(d) Less accumulated depreciation of $252.9 million and $229.1 million for Alliant Energy as of December 31, 2015 and 2014, respectively.

Schedule Of 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
	2015		2014		2013		2015		2014		2013		2015		2014		2013
Equity		$24.4		$23.1		$20.3		$18.6		$17.1		$13.8		$5.8		$6.0		$6.5
Debt	12.5		11.7		10.5		9.6		8.8		7.2		2.9		2.9		3.3
		$36.9		$34.8		$30.8		$28.2		$25.9		$21.0		$8.7		$8.9		$9.8

Schedule Of Allowance for Funds Used During Construction By Project

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

	2015		2014		2013
IPL:
Marshalltown		$20.7		$3.7		$—
Environmental controls - Ottumwa Unit 1	—		10.6		8.0
Environmental controls - George Neal Units 3 and 4	—		1.4		5.1
Other	7.5		10.2		7.9
	28.2		25.9		21.0
WPL:
Environmental controls - Edgewater Unit 5	5.1		2.7		—
Environmental controls - Columbia Units 1 and 2	—		4.0		7.2
Other	3.6		2.2		2.6
	8.7		8.9		9.8
Alliant Energy		$36.9		$34.8		$30.8

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
	2015			2014			2015			2014			2015			2014
Utility:
Electric plant:
In service:
Generation		$5,643.7			$5,463.0			$3,011.6			$2,872.4			$2,632.1			$2,590.6
Distribution	4,489.9			4,435.4			2,447.9			2,471.7			2,042.0			1,963.7
Other	311.3			309.1			212.2			215.5			99.1			93.6
Anticipated to be retired early (a)	—			157.6			—			—			—			157.6
Total electric plant	10,444.9			10,365.1			5,671.7			5,559.6			4,773.2			4,805.5
Gas plant in service	1,018.3			946.2			513.6			474.0			504.7			472.2
Other plant in service	530.6			539.3			296.0			298.8			234.6			240.5
Accumulated depreciation (a)	(3,939.6		)	(3,923.1		)	(2,152.8		)	(2,124.5		)	(1,786.8		)	(1,798.6		)
Net plant	8,054.2			7,927.5			4,328.5			4,207.9			3,725.7			3,719.6
Leased Sheboygan Falls Energy Facility, net (b)	—			—			—			—			58.6			64.7
Construction work in progress	897.5			479.1			578.2			325.0			319.3			154.1
Other, net	18.5			22.3			18.4			21.8			0.1			0.5
Total utility	8,970.2			8,428.9			4,925.1			4,554.7			4,103.7			3,938.9
Non-regulated and other:
Non-regulated Generation, net (c)	229.3			240.1			—			—			—			—
Corporate Services and other, net (d)	319.6			269.4			—			—			—			—
Total non-regulated and other	548.9			509.5			—			—			—			—
Total property, plant and equipment		$9,519.1			$8,938.4			$4,925.1			$4,554.7			$4,103.7			$3,938.9

(a) In December 2015, WPL retired Nelson Dewey Units 1 and 2 and Edgewater Unit 3 and transferred the remaining net book value from property, plant and equipment to regulatory assets pursuant to orders from the PSCW and FERC. Refer to Note 2 for discussion of the recovery of the remaining net book value of these EGUs.

(b) Less accumulated amortization of $65.2 million and $59.1 million for WPL as of December 31, 2015 and 2014, respectively.

(c) Less accumulated depreciation of $59.0 million and $49.5 million for Alliant Energy as of December 31, 2015 and 2014, respectively.

(d) Less accumulated depreciation of $252.9 million and $229.1 million for Alliant Energy as of December 31, 2015 and 2014, respectively.

Schedule Of 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
	2015		2014		2013		2015		2014		2013		2015		2014		2013
Equity		$24.4		$23.1		$20.3		$18.6		$17.1		$13.8		$5.8		$6.0		$6.5
Debt	12.5		11.7		10.5		9.6		8.8		7.2		2.9		2.9		3.3
		$36.9		$34.8		$30.8		$28.2		$25.9		$21.0		$8.7		$8.9		$9.8

Schedule Of Allowance for Funds Used During Construction By Project

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

	2015		2014		2013
IPL:
Marshalltown		$20.7		$3.7		$—
Environmental controls - Ottumwa Unit 1	—		10.6		8.0
Environmental controls - George Neal Units 3 and 4	—		1.4		5.1
Other	7.5		10.2		7.9
	28.2		25.9		21.0
WPL:
Environmental controls - Edgewater Unit 5	5.1		2.7		—
Environmental controls - Columbia Units 1 and 2	—		4.0		7.2
Other	3.6		2.2		2.6
	8.7		8.9		9.8
Alliant Energy		$36.9		$34.8		$30.8

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
	2015			2014			2015			2014			2015			2014
Utility:
Electric plant:
In service:
Generation		$5,643.7			$5,463.0			$3,011.6			$2,872.4			$2,632.1			$2,590.6
Distribution	4,489.9			4,435.4			2,447.9			2,471.7			2,042.0			1,963.7
Other	311.3			309.1			212.2			215.5			99.1			93.6
Anticipated to be retired early (a)	—			157.6			—			—			—			157.6
Total electric plant	10,444.9			10,365.1			5,671.7			5,559.6			4,773.2			4,805.5
Gas plant in service	1,018.3			946.2			513.6			474.0			504.7			472.2
Other plant in service	530.6			539.3			296.0			298.8			234.6			240.5
Accumulated depreciation (a)	(3,939.6		)	(3,923.1		)	(2,152.8		)	(2,124.5		)	(1,786.8		)	(1,798.6		)
Net plant	8,054.2			7,927.5			4,328.5			4,207.9			3,725.7			3,719.6
Leased Sheboygan Falls Energy Facility, net (b)	—			—			—			—			58.6			64.7
Construction work in progress	897.5			479.1			578.2			325.0			319.3			154.1
Other, net	18.5			22.3			18.4			21.8			0.1			0.5
Total utility	8,970.2			8,428.9			4,925.1			4,554.7			4,103.7			3,938.9
Non-regulated and other:
Non-regulated Generation, net (c)	229.3			240.1			—			—			—			—
Corporate Services and other, net (d)	319.6			269.4			—			—			—			—
Total non-regulated and other	548.9			509.5			—			—			—			—
Total property, plant and equipment		$9,519.1			$8,938.4			$4,925.1			$4,554.7			$4,103.7			$3,938.9

(a) In December 2015, WPL retired Nelson Dewey Units 1 and 2 and Edgewater Unit 3 and transferred the remaining net book value from property, plant and equipment to regulatory assets pursuant to orders from the PSCW and FERC. Refer to Note 2 for discussion of the recovery of the remaining net book value of these EGUs.

(b) Less accumulated amortization of $65.2 million and $59.1 million for WPL as of December 31, 2015 and 2014, respectively.

(c) Less accumulated depreciation of $59.0 million and $49.5 million for Alliant Energy as of December 31, 2015 and 2014, respectively.

(d) Less accumulated depreciation of $252.9 million and $229.1 million for Alliant Energy as of December 31, 2015 and 2014, respectively.

Schedule Of 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
	2015		2014		2013		2015		2014		2013		2015		2014		2013
Equity		$24.4		$23.1		$20.3		$18.6		$17.1		$13.8		$5.8		$6.0		$6.5
Debt	12.5		11.7		10.5		9.6		8.8		7.2		2.9		2.9		3.3
		$36.9		$34.8		$30.8		$28.2		$25.9		$21.0		$8.7		$8.9		$9.8

Schedule Of Allowance for Funds Used During Construction By Project

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

	2015		2014		2013
IPL:
Marshalltown		$20.7		$3.7		$—
Environmental controls - Ottumwa Unit 1	—		10.6		8.0
Environmental controls - George Neal Units 3 and 4	—		1.4		5.1
Other	7.5		10.2		7.9
	28.2		25.9		21.0
WPL:
Environmental controls - Edgewater Unit 5	5.1		2.7		—
Environmental controls - Columbia Units 1 and 2	—		4.0		7.2
Other	3.6		2.2		2.6
	8.7		8.9		9.8
Alliant Energy		$36.9		$34.8		$30.8