Jointly-Owned Electric Utility Plant (Tables)

12 Months Ended

Dec. 31, 2020

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 EGUs at December 31, 2020 was as follows (dollars in millions):

	Ownership	Electric	Accumulated Provision	Construction
	Interest %	Plant	for Depreciation	Work in Progress
IPL
Ottumwa Unit 1	48.0%	$580	$195	$22
George Neal Unit 4	25.7%	192	96	2
George Neal Unit 3	28.0%	171	67	—
Louisa Unit 1	4.0%	39	22	—
		982	380	24
WPL
Columbia Units 1-2	53.5%	786	289	4
West Riverside	91.8%	686	12	13
Forward Wind Energy Center	42.6%	120	46	—
		1,592	347	17
Alliant Energy		$2,574	$727	$41

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 EGUs at December 31, 2020 was as follows (dollars in millions):

	Ownership	Electric	Accumulated Provision	Construction
	Interest %	Plant	for Depreciation	Work in Progress
IPL
Ottumwa Unit 1	48.0%	$580	$195	$22
George Neal Unit 4	25.7%	192	96	2
George Neal Unit 3	28.0%	171	67	—
Louisa Unit 1	4.0%	39	22	—
		982	380	24
WPL
Columbia Units 1-2	53.5%	786	289	4
West Riverside	91.8%	686	12	13
Forward Wind Energy Center	42.6%	120	46	—
		1,592	347	17
Alliant Energy		$2,574	$727	$41

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 EGUs at December 31, 2020 was as follows (dollars in millions):

	Ownership	Electric	Accumulated Provision	Construction
	Interest %	Plant	for Depreciation	Work in Progress
IPL
Ottumwa Unit 1	48.0%	$580	$195	$22
George Neal Unit 4	25.7%	192	96	2
George Neal Unit 3	28.0%	171	67	—
Louisa Unit 1	4.0%	39	22	—
		982	380	24
WPL
Columbia Units 1-2	53.5%	786	289	4
West Riverside	91.8%	686	12	13
Forward Wind Energy Center	42.6%	120	46	—
		1,592	347	17
Alliant Energy		$2,574	$727	$41