Asset Retirement Obligations (Tables)

12 Months Ended

Dec. 31, 2023

Schedule of Asset Retirement Obligations [Line Items]

Reconciliation Of Changes In Asset Retirement Obligations (AROs)

A reconciliation of the changes in AROs associated with long-lived assets is as follows (in millions):

	Alliant Energy		IPL		WPL
	2023	2022	2023	2022	2023	2022
Balance, January 1	$279	$294	$195	$213	$84	$81
Revisions in estimated cash flows	(6)	19	(9)	15	3	4
Liabilities settled	(51)	(48)	(44)	(39)	(7)	(9)
Liabilities incurred	16	6	1	—	15	6
Accretion expense	8	8	5	6	3	2
Balance, December 31	$246	$279	$148	$195	$98	$84

IPL [Member]

Schedule of Asset Retirement Obligations [Line Items]

Reconciliation Of Changes In Asset Retirement Obligations (AROs)

A reconciliation of the changes in AROs associated with long-lived assets is as follows (in millions):

	Alliant Energy		IPL		WPL
	2023	2022	2023	2022	2023	2022
Balance, January 1	$279	$294	$195	$213	$84	$81
Revisions in estimated cash flows	(6)	19	(9)	15	3	4
Liabilities settled	(51)	(48)	(44)	(39)	(7)	(9)
Liabilities incurred	16	6	1	—	15	6
Accretion expense	8	8	5	6	3	2
Balance, December 31	$246	$279	$148	$195	$98	$84

WPL [Member]

Schedule of Asset Retirement Obligations [Line Items]

Reconciliation Of Changes In Asset Retirement Obligations (AROs)

A reconciliation of the changes in AROs associated with long-lived assets is as follows (in millions):

	Alliant Energy		IPL		WPL
	2023	2022	2023	2022	2023	2022
Balance, January 1	$279	$294	$195	$213	$84	$81
Revisions in estimated cash flows	(6)	19	(9)	15	3	4
Liabilities settled	(51)	(48)	(44)	(39)	(7)	(9)
Liabilities incurred	16	6	1	—	15	6
Accretion expense	8	8	5	6	3	2
Balance, December 31	$246	$279	$148	$195	$98	$84