Derivative Instruments (Tables)

3 Months Ended

Mar. 31, 2025

Derivative Instruments [Line Items]

Notional Amounts Of Derivative Instruments

As of March 31, 2025, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and financial transmission rights (FTRs) that were accounted for as commodity derivative instruments were as follows (units in thousands; megawatt-hour (MWh); dekatherm (Dth)):

	Electricity		FTRs		Natural Gas		Diesel Fuel
	MWhs	Years	MWhs	Years	Dths	Years	Gallons	Years
Alliant Energy	1,883	2025-2026	4,080	2025	158,493	2025-2032	1,890	2025
IPL	544	2025-2026	1,432	2025	67,874	2025-2030	—	—
WPL	1,339	2025-2026	2,648	2025	90,619	2025-2032	1,890	2025

Fair Value Of Financial Instruments

Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions):

	Alliant Energy		IPL		WPL
	March 31, 2025	December 31, 2024	March 31, 2025	December 31, 2024	March 31, 2025	December 31, 2024
Current derivative assets	$44	$41	$26	$29	$18	$12
Non-current derivative assets	26	34	14	19	12	15
Current derivative liabilities	16	26	6	11	10	15
Non-current derivative liabilities	36	32	4	2	32	30

Balance Sheet Offsetting

However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions):

	Alliant Energy		IPL		WPL
	Gross		Gross		Gross
	(as reported)	Net	(as reported)	Net	(as reported)	Net
March 31, 2025
Derivative assets	$70	$59	$40	$35	$30	$24
Derivative liabilities	52	41	10	5	42	36
December 31, 2024
Derivative assets	75	64	48	43	27	21
Derivative liabilities	58	47	13	8	45	39

IPL [Member]

Derivative Instruments [Line Items]

Notional Amounts Of Derivative Instruments

As of March 31, 2025, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and financial transmission rights (FTRs) that were accounted for as commodity derivative instruments were as follows (units in thousands; megawatt-hour (MWh); dekatherm (Dth)):

	Electricity		FTRs		Natural Gas		Diesel Fuel
	MWhs	Years	MWhs	Years	Dths	Years	Gallons	Years
Alliant Energy	1,883	2025-2026	4,080	2025	158,493	2025-2032	1,890	2025
IPL	544	2025-2026	1,432	2025	67,874	2025-2030	—	—
WPL	1,339	2025-2026	2,648	2025	90,619	2025-2032	1,890	2025

Fair Value Of Financial Instruments

Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions):

	Alliant Energy		IPL		WPL
	March 31, 2025	December 31, 2024	March 31, 2025	December 31, 2024	March 31, 2025	December 31, 2024
Current derivative assets	$44	$41	$26	$29	$18	$12
Non-current derivative assets	26	34	14	19	12	15
Current derivative liabilities	16	26	6	11	10	15
Non-current derivative liabilities	36	32	4	2	32	30

Balance Sheet Offsetting

However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions):

	Alliant Energy		IPL		WPL
	Gross		Gross		Gross
	(as reported)	Net	(as reported)	Net	(as reported)	Net
March 31, 2025
Derivative assets	$70	$59	$40	$35	$30	$24
Derivative liabilities	52	41	10	5	42	36
December 31, 2024
Derivative assets	75	64	48	43	27	21
Derivative liabilities	58	47	13	8	45	39

WPL [Member]

Derivative Instruments [Line Items]

Notional Amounts Of Derivative Instruments

As of March 31, 2025, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and financial transmission rights (FTRs) that were accounted for as commodity derivative instruments were as follows (units in thousands; megawatt-hour (MWh); dekatherm (Dth)):

	Electricity		FTRs		Natural Gas		Diesel Fuel
	MWhs	Years	MWhs	Years	Dths	Years	Gallons	Years
Alliant Energy	1,883	2025-2026	4,080	2025	158,493	2025-2032	1,890	2025
IPL	544	2025-2026	1,432	2025	67,874	2025-2030	—	—
WPL	1,339	2025-2026	2,648	2025	90,619	2025-2032	1,890	2025

Fair Value Of Financial Instruments

Derivative instruments are recorded at fair value each reporting date on the balance sheets as assets or liabilities as follows (in millions):

	Alliant Energy		IPL		WPL
	March 31, 2025	December 31, 2024	March 31, 2025	December 31, 2024	March 31, 2025	December 31, 2024
Current derivative assets	$44	$41	$26	$29	$18	$12
Non-current derivative assets	26	34	14	19	12	15
Current derivative liabilities	16	26	6	11	10	15
Non-current derivative liabilities	36	32	4	2	32	30

Balance Sheet Offsetting

However, if the fair value amounts of derivative instruments by counterparty were netted, derivative assets and derivative liabilities related to commodity contracts would have been presented on the balance sheets as follows (in millions):

	Alliant Energy		IPL		WPL
	Gross		Gross		Gross
	(as reported)	Net	(as reported)	Net	(as reported)	Net
March 31, 2025
Derivative assets	$70	$59	$40	$35	$30	$24
Derivative liabilities	52	41	10	5	42	36
December 31, 2024
Derivative assets	75	64	48	43	27	21
Derivative liabilities	58	47	13	8	45	39