Debt (Tables)

3 Months Ended

Mar. 31, 2021

Short-term Debt [Line Items]

Other Short-Term Borrowings

Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper, and Alliant Energy’s and WPL’s borrowings under the single credit facility, which currently expires in August 2023, classified as short-term debt was as follows (dollars in millions):

March 31, 2021	Alliant Energy	IPL	WPL
Amount outstanding	$336	$—	$148
Weighted average interest rates	0.2%	N/A	0.1%
Available credit facility capacity	$664	$250	$152

	Alliant Energy		IPL		WPL
Three Months Ended March 31	2021	2020	2021	2020	2021	2020
Maximum amount outstanding (based on daily outstanding balances)	$578	$463	$—	$1	$275	$212
Average amount outstanding (based on daily outstanding balances)	$424	$382	$—	$—	$189	$167
Weighted average interest rates	0.2%	1.8%	—%	1.8%	0.2%	1.8%

IPL [Member]

Short-term Debt [Line Items]

Other Short-Term Borrowings

Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper, and Alliant Energy’s and WPL’s borrowings under the single credit facility, which currently expires in August 2023, classified as short-term debt was as follows (dollars in millions):

March 31, 2021	Alliant Energy	IPL	WPL
Amount outstanding	$336	$—	$148
Weighted average interest rates	0.2%	N/A	0.1%
Available credit facility capacity	$664	$250	$152

	Alliant Energy		IPL		WPL
Three Months Ended March 31	2021	2020	2021	2020	2021	2020
Maximum amount outstanding (based on daily outstanding balances)	$578	$463	$—	$1	$275	$212
Average amount outstanding (based on daily outstanding balances)	$424	$382	$—	$—	$189	$167
Weighted average interest rates	0.2%	1.8%	—%	1.8%	0.2%	1.8%

WPL [Member]

Short-term Debt [Line Items]

Other Short-Term Borrowings

Information regarding Alliant Energy’s, IPL’s and WPL’s commercial paper, and Alliant Energy’s and WPL’s borrowings under the single credit facility, which currently expires in August 2023, classified as short-term debt was as follows (dollars in millions):

March 31, 2021	Alliant Energy	IPL	WPL
Amount outstanding	$336	$—	$148
Weighted average interest rates	0.2%	N/A	0.1%
Available credit facility capacity	$664	$250	$152

	Alliant Energy		IPL		WPL
Three Months Ended March 31	2021	2020	2021	2020	2021	2020
Maximum amount outstanding (based on daily outstanding balances)	$578	$463	$—	$1	$275	$212
Average amount outstanding (based on daily outstanding balances)	$424	$382	$—	$—	$189	$167
Weighted average interest rates	0.2%	1.8%	—%	1.8%	0.2%	1.8%