Leases (Tables)

12 Months Ended

Dec. 31, 2021

Leases [Line Items]

Schedule of Operating Lease Details

Operating lease details are as follows (dollars in millions):

	December 31, 2021			December 31, 2020
	Alliant Energy	IPL	WPL	Alliant Energy	IPL	WPL
Property, plant and equipment, net	$14	$9	$5	$15	$9	$6
Other current liabilities	$2	$1	$1	$2	$1	$1
Other liabilities	12	8	4	13	8	5
Total operating lease liabilities	$14	$9	$5	$15	$9	$6
Weighted average remaining lease term	9 years	11 years	8 years	10 years	11 years	9 years
Weighted average discount rate	4%	4%	4%	4%	4%	4%

Schedule of Finance Lease Details

Finance lease details are as follows (dollars in millions):

	Alliant Energy	WPL
	December 31, 2021	December 31, 2021	December 31, 2020
Property, plant and equipment, net:
Sheboygan Falls Energy Facility	n/a	$21	$27
Leased land for solar generation	$11	11	—
	$11	$32	$27
Other current liabilities:
Sheboygan Falls Energy Facility	n/a	$10	$9
Leased land for solar generation	$1	1	—
	1	11	9
Other liabilities:
Sheboygan Falls Energy Facility	n/a	31	42
Leased land for solar generation	11	11	—
	11	42	42
Total finance lease liabilities	$12	$53	$51
Weighted average remaining lease term	34 years	10 years	4 years
Weighted average discount rate	3%	9%	11%
	2021	2021	2020	2019
Depreciation and amortization expenses	$—	$6	$6	$6
Interest expense	—	5	6	7
Total finance lease expense	$—	$11	$12	$13

Schedule of Operating Lease Liability Maturities

As of December 31, 2021, expected maturities of lease liabilities were as follows (in millions):

	2022	2023	2024	2025	2026	Thereafter	Total	Less: amount representing interest	Present value of minimum lease payments
Operating Leases:
Alliant Energy	$2	$2	$2	$2	$2	$7	$17	$3	$14
IPL	1	1	1	1	1	6	11	2	9
WPL	1	1	1	1	1	1	6	1	5
Finance Leases:
Alliant Energy	—	—	—	—	1	19	20	8	12
WPL	15	15	15	6	1	19	71	18	53

Schedule of Finance Lease Liability Maturities

As of December 31, 2021, expected maturities of lease liabilities were as follows (in millions):

	2022	2023	2024	2025	2026	Thereafter	Total	Less: amount representing interest	Present value of minimum lease payments
Operating Leases:
Alliant Energy	$2	$2	$2	$2	$2	$7	$17	$3	$14
IPL	1	1	1	1	1	6	11	2	9
WPL	1	1	1	1	1	1	6	1	5
Finance Leases:
Alliant Energy	—	—	—	—	1	19	20	8	12
WPL	15	15	15	6	1	19	71	18	53

IPL [Member]

Leases [Line Items]

Schedule of Operating Lease Details

Operating lease details are as follows (dollars in millions):

	December 31, 2021			December 31, 2020
	Alliant Energy	IPL	WPL	Alliant Energy	IPL	WPL
Property, plant and equipment, net	$14	$9	$5	$15	$9	$6
Other current liabilities	$2	$1	$1	$2	$1	$1
Other liabilities	12	8	4	13	8	5
Total operating lease liabilities	$14	$9	$5	$15	$9	$6
Weighted average remaining lease term	9 years	11 years	8 years	10 years	11 years	9 years
Weighted average discount rate	4%	4%	4%	4%	4%	4%

Schedule of Operating Lease Liability Maturities

As of December 31, 2021, expected maturities of lease liabilities were as follows (in millions):

	2022	2023	2024	2025	2026	Thereafter	Total	Less: amount representing interest	Present value of minimum lease payments
Operating Leases:
Alliant Energy	$2	$2	$2	$2	$2	$7	$17	$3	$14
IPL	1	1	1	1	1	6	11	2	9
WPL	1	1	1	1	1	1	6	1	5
Finance Leases:
Alliant Energy	—	—	—	—	1	19	20	8	12
WPL	15	15	15	6	1	19	71	18	53

WPL [Member]

Leases [Line Items]

Schedule of Operating Lease Details

Operating lease details are as follows (dollars in millions):

	December 31, 2021			December 31, 2020
	Alliant Energy	IPL	WPL	Alliant Energy	IPL	WPL
Property, plant and equipment, net	$14	$9	$5	$15	$9	$6
Other current liabilities	$2	$1	$1	$2	$1	$1
Other liabilities	12	8	4	13	8	5
Total operating lease liabilities	$14	$9	$5	$15	$9	$6
Weighted average remaining lease term	9 years	11 years	8 years	10 years	11 years	9 years
Weighted average discount rate	4%	4%	4%	4%	4%	4%

Schedule of Finance Lease Details

Finance lease details are as follows (dollars in millions):

	Alliant Energy	WPL
	December 31, 2021	December 31, 2021	December 31, 2020
Property, plant and equipment, net:
Sheboygan Falls Energy Facility	n/a	$21	$27
Leased land for solar generation	$11	11	—
	$11	$32	$27
Other current liabilities:
Sheboygan Falls Energy Facility	n/a	$10	$9
Leased land for solar generation	$1	1	—
	1	11	9
Other liabilities:
Sheboygan Falls Energy Facility	n/a	31	42
Leased land for solar generation	11	11	—
	11	42	42
Total finance lease liabilities	$12	$53	$51
Weighted average remaining lease term	34 years	10 years	4 years
Weighted average discount rate	3%	9%	11%
	2021	2021	2020	2019
Depreciation and amortization expenses	$—	$6	$6	$6
Interest expense	—	5	6	7
Total finance lease expense	$—	$11	$12	$13

Schedule of Operating Lease Liability Maturities

As of December 31, 2021, expected maturities of lease liabilities were as follows (in millions):

	2022	2023	2024	2025	2026	Thereafter	Total	Less: amount representing interest	Present value of minimum lease payments
Operating Leases:
Alliant Energy	$2	$2	$2	$2	$2	$7	$17	$3	$14
IPL	1	1	1	1	1	6	11	2	9
WPL	1	1	1	1	1	1	6	1	5
Finance Leases:
Alliant Energy	—	—	—	—	1	19	20	8	12
WPL	15	15	15	6	1	19	71	18	53

Schedule of Finance Lease Liability Maturities

As of December 31, 2021, expected maturities of lease liabilities were as follows (in millions):

	2022	2023	2024	2025	2026	Thereafter	Total	Less: amount representing interest	Present value of minimum lease payments
Operating Leases:
Alliant Energy	$2	$2	$2	$2	$2	$7	$17	$3	$14
IPL	1	1	1	1	1	6	11	2	9
WPL	1	1	1	1	1	1	6	1	5
Finance Leases:
Alliant Energy	—	—	—	—	1	19	20	8	12
WPL	15	15	15	6	1	19	71	18	53