Jointly-Owned Electric Utility Plant (Tables)

12 Months Ended

Dec. 31, 2015

Jointly Owned Electric Utility Plant [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 EGUs at December 31, 2015 was as follows (dollars in millions):

						Accumulated		Construction
	In-service	Ownership		Electric		Provision for		Work in
	Dates	Interest %		Plant		Depreciation		Progress
IPL
Ottumwa Unit 1	1981	48.0	%		$481.4		$125.0		$6.5
George Neal Unit 4	1979	25.7	%	184.3		76.3		0.2
George Neal Unit 3	1975	28.0	%	150.0		45.1		0.1
Louisa Unit 1	1983	4.0	%	36.4		21.1		0.1
				852.1		267.5		6.9
WPL
Columbia Units 1-2	1975-1978	46.2	%	571.9		175.5		34.8
Edgewater Unit 4	1969	68.2	%	102.7		58.2		0.1
				674.6		233.7		34.9
Alliant Energy					$1,526.7		$501.2		$41.8

IPL [Member]

Jointly Owned Electric Utility Plant [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 EGUs at December 31, 2015 was as follows (dollars in millions):

						Accumulated		Construction
	In-service	Ownership		Electric		Provision for		Work in
	Dates	Interest %		Plant		Depreciation		Progress
IPL
Ottumwa Unit 1	1981	48.0	%		$481.4		$125.0		$6.5
George Neal Unit 4	1979	25.7	%	184.3		76.3		0.2
George Neal Unit 3	1975	28.0	%	150.0		45.1		0.1
Louisa Unit 1	1983	4.0	%	36.4		21.1		0.1
				852.1		267.5		6.9
WPL
Columbia Units 1-2	1975-1978	46.2	%	571.9		175.5		34.8
Edgewater Unit 4	1969	68.2	%	102.7		58.2		0.1
				674.6		233.7		34.9
Alliant Energy					$1,526.7		$501.2		$41.8

WPL [Member]

Jointly Owned Electric Utility Plant [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 EGUs at December 31, 2015 was as follows (dollars in millions):

						Accumulated		Construction
	In-service	Ownership		Electric		Provision for		Work in
	Dates	Interest %		Plant		Depreciation		Progress
IPL
Ottumwa Unit 1	1981	48.0	%		$481.4		$125.0		$6.5
George Neal Unit 4	1979	25.7	%	184.3		76.3		0.2
George Neal Unit 3	1975	28.0	%	150.0		45.1		0.1
Louisa Unit 1	1983	4.0	%	36.4		21.1		0.1
				852.1		267.5		6.9
WPL
Columbia Units 1-2	1975-1978	46.2	%	571.9		175.5		34.8
Edgewater Unit 4	1969	68.2	%	102.7		58.2		0.1
				674.6		233.7		34.9
Alliant Energy					$1,526.7		$501.2		$41.8