Valuation and Qualifying Accounts And Reserves

12 Months Ended

Dec. 31, 2023

SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]

Valuation and Qualifying Accounts And Reserves

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES

		Additions
	Balance,	(Charged to		Balance,
Description	January 1	Expense)	Deductions (a)	December 31
	(in millions)

Valuation and Qualifying Accounts Which are Deducted in the Balance Sheet from the Assets to Which They Apply:

Accumulated Provision for Uncollectible Accounts:
	Alliant Energy (b)
		Year ended December 31, 2023	$7	$20	$19	$8
		Year ended December 31, 2022	11	17	21	7
		Year ended December 31, 2021	18	12	19	11
	IPL (b)
		Year ended December 31, 2023	$—	$11	$11	$—
		Year ended December 31, 2022	1	7	8	—
		Year ended December 31, 2021	1	6	6	1
	WPL
		Year ended December 31, 2023	$7	$9	$8	$8
		Year ended December 31, 2022	10	10	13	7
		Year ended December 31, 2021	17	6	13	10

Note: The above provisions relate to various customer, notes and other receivable balances included in various line items on the respective balance sheets.

(a)Deductions are of the nature for which the reserves were created. In the case of the accumulated provision for uncollectible accounts, deductions from this reserve are reduced by recoveries of amounts previously written off.

(b)Refer to Note 5(b) for discussion of IPL’s sales of accounts receivable program.

IPL [Member]

SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]

Valuation and Qualifying Accounts And Reserves

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES

		Additions
	Balance,	(Charged to		Balance,
Description	January 1	Expense)	Deductions (a)	December 31
	(in millions)

Valuation and Qualifying Accounts Which are Deducted in the Balance Sheet from the Assets to Which They Apply:

Accumulated Provision for Uncollectible Accounts:
	Alliant Energy (b)
		Year ended December 31, 2023	$7	$20	$19	$8
		Year ended December 31, 2022	11	17	21	7
		Year ended December 31, 2021	18	12	19	11
	IPL (b)
		Year ended December 31, 2023	$—	$11	$11	$—
		Year ended December 31, 2022	1	7	8	—
		Year ended December 31, 2021	1	6	6	1
	WPL
		Year ended December 31, 2023	$7	$9	$8	$8
		Year ended December 31, 2022	10	10	13	7
		Year ended December 31, 2021	17	6	13	10

Note: The above provisions relate to various customer, notes and other receivable balances included in various line items on the respective balance sheets.

(a)Deductions are of the nature for which the reserves were created. In the case of the accumulated provision for uncollectible accounts, deductions from this reserve are reduced by recoveries of amounts previously written off.

(b)Refer to Note 5(b) for discussion of IPL’s sales of accounts receivable program.

WPL [Member]

SEC Schedule, 12-09, Valuation and Qualifying Accounts Disclosure [Line Items]

Valuation and Qualifying Accounts And Reserves

SCHEDULE II - VALUATION AND QUALIFYING ACCOUNTS AND RESERVES

		Additions
	Balance,	(Charged to		Balance,
Description	January 1	Expense)	Deductions (a)	December 31
	(in millions)

Valuation and Qualifying Accounts Which are Deducted in the Balance Sheet from the Assets to Which They Apply:

Accumulated Provision for Uncollectible Accounts:
	Alliant Energy (b)
		Year ended December 31, 2023	$7	$20	$19	$8
		Year ended December 31, 2022	11	17	21	7
		Year ended December 31, 2021	18	12	19	11
	IPL (b)
		Year ended December 31, 2023	$—	$11	$11	$—
		Year ended December 31, 2022	1	7	8	—
		Year ended December 31, 2021	1	6	6	1
	WPL
		Year ended December 31, 2023	$7	$9	$8	$8
		Year ended December 31, 2022	10	10	13	7
		Year ended December 31, 2021	17	6	13	10

Note: The above provisions relate to various customer, notes and other receivable balances included in various line items on the respective balance sheets.

(a)Deductions are of the nature for which the reserves were created. In the case of the accumulated provision for uncollectible accounts, deductions from this reserve are reduced by recoveries of amounts previously written off.

(b)Refer to Note 5(b) for discussion of IPL’s sales of accounts receivable program.