v2.4.0.6

Jointly-Owned Electric Utility Plant (Tables)

12 Months Ended

Dec. 31, 2012

Jointly Owned Utility Plant Interests [Line Items]

Components of Jointly-Owned Electric Utility Plants

Information relative to IPL’s and WPL’s ownership interest in these jointly-owned coal-fired electric generating facilities at December 31, 2012 was as follows (dollars in millions):

										Accumulated				Construction				Cost of Removal
	In-service		Ownership			Plant in				Provision for				Work in				Obligations Included in
	Dates		Interest %			Service				Depreciation				Progress				Regulatory Liabilities
IPL
Ottumwa Unit 1	1981		48.0	%			$239.2				$118.8				$84.0				$12.0
George Neal Unit 4	1979		25.7	%		97.1				67.8				44.5				11.5
George Neal Unit 3	1975		28.0	%		59.1				39.1				27.2				5.6
Louisa Unit 1	1983		4.0	%		35.0				19.2				0.2				3.0
						430.4				244.9				155.9				32.1
WPL
Columbia Units 1-2	1975-1978		46.2	%		247.0				157.9				133.5				10.2
Edgewater Unit 4	1969		68.2	%		91.8				49.2				0.4				2.2
						338.8				207.1				133.9				12.4
Alliant Energy							$769.2				$452.0				$289.8				$44.5

IPL [Member]

Jointly Owned Utility Plant Interests [Line Items]

Components of Jointly-Owned Electric Utility Plants

Information relative to IPL’s and WPL’s ownership interest in these jointly-owned coal-fired electric generating facilities at December 31, 2012 was as follows (dollars in millions):

										Accumulated				Construction				Cost of Removal
	In-service		Ownership			Plant in				Provision for				Work in				Obligations Included in
	Dates		Interest %			Service				Depreciation				Progress				Regulatory Liabilities
IPL
Ottumwa Unit 1	1981		48.0	%			$239.2				$118.8				$84.0				$12.0
George Neal Unit 4	1979		25.7	%		97.1				67.8				44.5				11.5
George Neal Unit 3	1975		28.0	%		59.1				39.1				27.2				5.6
Louisa Unit 1	1983		4.0	%		35.0				19.2				0.2				3.0
						430.4				244.9				155.9				32.1
WPL
Columbia Units 1-2	1975-1978		46.2	%		247.0				157.9				133.5				10.2
Edgewater Unit 4	1969		68.2	%		91.8				49.2				0.4				2.2
						338.8				207.1				133.9				12.4
Alliant Energy							$769.2				$452.0				$289.8				$44.5

WPL [Member]

Jointly Owned Utility Plant Interests [Line Items]

Components of Jointly-Owned Electric Utility Plants

Information relative to IPL’s and WPL’s ownership interest in these jointly-owned coal-fired electric generating facilities at December 31, 2012 was as follows (dollars in millions):

										Accumulated				Construction				Cost of Removal
	In-service		Ownership			Plant in				Provision for				Work in				Obligations Included in
	Dates		Interest %			Service				Depreciation				Progress				Regulatory Liabilities
IPL
Ottumwa Unit 1	1981		48.0	%			$239.2				$118.8				$84.0				$12.0
George Neal Unit 4	1979		25.7	%		97.1				67.8				44.5				11.5
George Neal Unit 3	1975		28.0	%		59.1				39.1				27.2				5.6
Louisa Unit 1	1983		4.0	%		35.0				19.2				0.2				3.0
						430.4				244.9				155.9				32.1
WPL
Columbia Units 1-2	1975-1978		46.2	%		247.0				157.9				133.5				10.2
Edgewater Unit 4	1969		68.2	%		91.8				49.2				0.4				2.2
						338.8				207.1				133.9				12.4
Alliant Energy							$769.2				$452.0				$289.8				$44.5

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X

- Definition

Tabular disclosure of proportionate interests in jointly owned utility plants. Includes the amount of plants in service, the accumulated provision for depreciation (if available), the amount of plants under construction, and the proportionate share. The amounts presented may be further subdivided to show amounts applicable to plant subcategories (for example, production, transmission, distribution). Includes statements that the amounts represent the utility's share in each joint plant and that it must provide its own financing. Information concerning two or more generating plants on the same site may be combined. States that the utility's share of direct expenses of the joint plants is included in the corresponding operating expenses on its income statement (for example, fuel, maintenance of plant, other operating expense). If the share of direct expenses is charged to purchased power, then disclose the amount so charged and the proportionate amounts charged to specific operating expenses on the records maintained for the joint plants.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 980

-SubTopic 360

-Section S99

-Paragraph 1

-Subparagraph (SAB TOPIC 10.C)

-URI http://asc.fasb.org/extlink&oid=6500719&loc=d3e659983-123033



Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 10

-Section C

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