Leases (Tables)

12 Months Ended

Dec. 31, 2020

Leases [Line Items]

Schedule of Lease Details

At December 31, operating lease details are as follows (dollars in millions):

	2020			2019
	Alliant Energy	IPL	WPL	Alliant Energy	IPL	WPL
Property, plant and equipment, net	$15	$9	$6	$16	$10	$6
Other current liabilities	$2	$1	$1	$2	$1	$1
Other liabilities	13	8	5	14	9	5
Total operating lease liabilities	$15	$9	$6	$16	$10	$6
Weighted average remaining lease term	10 years	11 years	9 years	11 years	12 years	10 years
Weighted average discount rate	4%	4%	4%	4%	4%	4%

Schedule of Operating Lease Liability Maturities

As of December 31, 2020, expected maturities of lease liabilities were as follows (in millions):

	2021	2022	2023	2024	2025	Thereafter	Total	Less: amount representing interest	Present value of minimum lease payments
Operating Leases:
Alliant Energy	$2	$2	$2	$2	$2	$8	$18	$3	$15
IPL	1	1	1	1	1	6	11	2	9
WPL	1	1	1	1	1	2	7	1	6
WPL’s Finance Lease:
Sheboygan Falls Energy Facility	15	15	15	15	5	—	65	14	51

IPL [Member]

Leases [Line Items]

Schedule of Lease Details

At December 31, operating lease details are as follows (dollars in millions):

	2020			2019
	Alliant Energy	IPL	WPL	Alliant Energy	IPL	WPL
Property, plant and equipment, net	$15	$9	$6	$16	$10	$6
Other current liabilities	$2	$1	$1	$2	$1	$1
Other liabilities	13	8	5	14	9	5
Total operating lease liabilities	$15	$9	$6	$16	$10	$6
Weighted average remaining lease term	10 years	11 years	9 years	11 years	12 years	10 years
Weighted average discount rate	4%	4%	4%	4%	4%	4%

Schedule of Operating Lease Liability Maturities

As of December 31, 2020, expected maturities of lease liabilities were as follows (in millions):

	2021	2022	2023	2024	2025	Thereafter	Total	Less: amount representing interest	Present value of minimum lease payments
Operating Leases:
Alliant Energy	$2	$2	$2	$2	$2	$8	$18	$3	$15
IPL	1	1	1	1	1	6	11	2	9
WPL	1	1	1	1	1	2	7	1	6
WPL’s Finance Lease:
Sheboygan Falls Energy Facility	15	15	15	15	5	—	65	14	51

WPL [Member]

Leases [Line Items]

Schedule of Lease Details

At December 31, operating lease details are as follows (dollars in millions):

	2020			2019
	Alliant Energy	IPL	WPL	Alliant Energy	IPL	WPL
Property, plant and equipment, net	$15	$9	$6	$16	$10	$6
Other current liabilities	$2	$1	$1	$2	$1	$1
Other liabilities	13	8	5	14	9	5
Total operating lease liabilities	$15	$9	$6	$16	$10	$6
Weighted average remaining lease term	10 years	11 years	9 years	11 years	12 years	10 years
Weighted average discount rate	4%	4%	4%	4%	4%	4%

WPL’s finance lease details are as follows (dollars in millions):

	December 31, 2020	December 31, 2019
Property, plant and equipment, net	$27	$32
Other current liabilities	$9	$9
Finance lease obligations - Sheboygan Falls Energy Facility	42	51
Total finance lease liabilities	$51	$60
Remaining lease term	4 years	5 years
Discount rate	11%	11%
	2020	2019
Depreciation expense	$6	$6
Interest expense	6	7
Total finance lease expense	$12	$13

Schedule of Operating Lease Liability Maturities

As of December 31, 2020, expected maturities of lease liabilities were as follows (in millions):

	2021	2022	2023	2024	2025	Thereafter	Total	Less: amount representing interest	Present value of minimum lease payments
Operating Leases:
Alliant Energy	$2	$2	$2	$2	$2	$8	$18	$3	$15
IPL	1	1	1	1	1	6	11	2	9
WPL	1	1	1	1	1	2	7	1	6
WPL’s Finance Lease:
Sheboygan Falls Energy Facility	15	15	15	15	5	—	65	14	51

Schedule of Finance Lease Liability Maturities

As of December 31, 2020, expected maturities of lease liabilities were as follows (in millions):

	2021	2022	2023	2024	2025	Thereafter	Total	Less: amount representing interest	Present value of minimum lease payments
Operating Leases:
Alliant Energy	$2	$2	$2	$2	$2	$8	$18	$3	$15
IPL	1	1	1	1	1	6	11	2	9
WPL	1	1	1	1	1	2	7	1	6
WPL’s Finance Lease:
Sheboygan Falls Energy Facility	15	15	15	15	5	—	65	14	51