Fair Value Measurements (Tables)

9 Months Ended

Sep. 30, 2023

Statement [Line Items]

Fair Value Measurements

Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):

Alliant Energy	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$189	$189	$—	$—	$189	$10	$10	$—	$—	$10
Commodity derivatives	129	—	80	49	129	237	—	206	31	237
Interest rate derivatives	6	—	6	—	6	—	—	—	—	—
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	66	—	60	6	66	79	—	67	12	79
Long-term debt (incl. current maturities)	8,838	—	7,863	—	7,863	8,076	—	7,338	1	7,339

IPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$180	$180	$—	$—	$180	$10	$10	$—	$—	$10
Commodity derivatives	85	—	45	40	85	138	—	111	27	138
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	21	—	16	5	21	46	—	35	11	46
Long-term debt	3,944	—	3,422	—	3,422	3,646	—	3,228	—	3,228

WPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Commodity derivatives	$44	$—	$35	$9	$44	$99	$—	$95	$4	$99
Liabilities:
Commodity derivatives	45	—	44	1	45	33	—	32	1	33
Long-term debt	3,069	—	2,722	—	2,722	2,770	—	2,542	—	2,542

Fair Value Measurements Using Significant Unobservable Inputs

Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$54	$72	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	17	(1)	—	—
Sales	(1)	—	—	—
Settlements (a)	(27)	(26)	61	4
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$17	($1)	$—	$—

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$19	$29	$185	$214
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(17)	—	—
Purchases	62	79	—	—
Sales	(2)	—	—	—
Settlements (a)	(42)	(46)	51	34
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($17)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$41	$58	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	12	(6)	—	—
Sales	(1)	—	—	—
Settlements (a)	(17)	(19)	61	4
Ending balance, September 30	$35	$33	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$12	($6)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$16	$18	$185	$214
Total net losses included in changes in net assets (realized/unrealized)	—	(13)	—	—
Purchases	51	58	—	—
Sales	(2)	—	—	—
Settlements (a)	(30)	(30)	51	34
Ending balance, September 30	$35	$33	$236	$248
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30	$—	($14)	$—	$—

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Three Months Ended September 30	2023	2022
Beginning balance, July 1	$13	$14
Total net gains included in changes in net assets (realized/unrealized)	5	5
Settlements	(10)	(7)
Ending balance, September 30	$8	$12
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$5	$5

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Nine Months Ended September 30	2023	2022
Beginning balance, January 1	$3	$11
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(4)
Purchases	11	21
Settlements	(12)	(16)
Ending balance, September 30	$8	$12
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($3)

(a)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.

Fair Value Of Net Derivative Assets (Liabilities)

The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions):

	Alliant Energy		IPL		WPL
	Excluding FTRs	FTRs	Excluding FTRs	FTRs	Excluding FTRs	FTRs
September 30, 2023	$3	$40	$4	$31	($1)	$9
December 31, 2022	(10)	29	(9)	25	(1)	4

IPL [Member]

Statement [Line Items]

Fair Value Measurements

Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):

Alliant Energy	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$189	$189	$—	$—	$189	$10	$10	$—	$—	$10
Commodity derivatives	129	—	80	49	129	237	—	206	31	237
Interest rate derivatives	6	—	6	—	6	—	—	—	—	—
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	66	—	60	6	66	79	—	67	12	79
Long-term debt (incl. current maturities)	8,838	—	7,863	—	7,863	8,076	—	7,338	1	7,339

IPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$180	$180	$—	$—	$180	$10	$10	$—	$—	$10
Commodity derivatives	85	—	45	40	85	138	—	111	27	138
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	21	—	16	5	21	46	—	35	11	46
Long-term debt	3,944	—	3,422	—	3,422	3,646	—	3,228	—	3,228

WPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Commodity derivatives	$44	$—	$35	$9	$44	$99	$—	$95	$4	$99
Liabilities:
Commodity derivatives	45	—	44	1	45	33	—	32	1	33
Long-term debt	3,069	—	2,722	—	2,722	2,770	—	2,542	—	2,542

Fair Value Measurements Using Significant Unobservable Inputs

Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$54	$72	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	17	(1)	—	—
Sales	(1)	—	—	—
Settlements (a)	(27)	(26)	61	4
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$17	($1)	$—	$—

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$19	$29	$185	$214
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(17)	—	—
Purchases	62	79	—	—
Sales	(2)	—	—	—
Settlements (a)	(42)	(46)	51	34
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($17)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$41	$58	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	12	(6)	—	—
Sales	(1)	—	—	—
Settlements (a)	(17)	(19)	61	4
Ending balance, September 30	$35	$33	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$12	($6)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$16	$18	$185	$214
Total net losses included in changes in net assets (realized/unrealized)	—	(13)	—	—
Purchases	51	58	—	—
Sales	(2)	—	—	—
Settlements (a)	(30)	(30)	51	34
Ending balance, September 30	$35	$33	$236	$248
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30	$—	($14)	$—	$—

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Three Months Ended September 30	2023	2022
Beginning balance, July 1	$13	$14
Total net gains included in changes in net assets (realized/unrealized)	5	5
Settlements	(10)	(7)
Ending balance, September 30	$8	$12
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$5	$5

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Nine Months Ended September 30	2023	2022
Beginning balance, January 1	$3	$11
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(4)
Purchases	11	21
Settlements	(12)	(16)
Ending balance, September 30	$8	$12
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($3)

(a)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.

Fair Value Of Net Derivative Assets (Liabilities)

The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions):

	Alliant Energy		IPL		WPL
	Excluding FTRs	FTRs	Excluding FTRs	FTRs	Excluding FTRs	FTRs
September 30, 2023	$3	$40	$4	$31	($1)	$9
December 31, 2022	(10)	29	(9)	25	(1)	4

WPL [Member]

Statement [Line Items]

Fair Value Measurements

Carrying amounts and related estimated fair values of other financial instruments were as follows (in millions):

Alliant Energy	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$189	$189	$—	$—	$189	$10	$10	$—	$—	$10
Commodity derivatives	129	—	80	49	129	237	—	206	31	237
Interest rate derivatives	6	—	6	—	6	—	—	—	—	—
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	66	—	60	6	66	79	—	67	12	79
Long-term debt (incl. current maturities)	8,838	—	7,863	—	7,863	8,076	—	7,338	1	7,339

IPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Money market fund investments	$180	$180	$—	$—	$180	$10	$10	$—	$—	$10
Commodity derivatives	85	—	45	40	85	138	—	111	27	138
Deferred proceeds	236	—	—	236	236	185	—	—	185	185
Liabilities:
Commodity derivatives	21	—	16	5	21	46	—	35	11	46
Long-term debt	3,944	—	3,422	—	3,422	3,646	—	3,228	—	3,228

WPL	September 30, 2023					December 31, 2022
		Fair Value					Fair Value
	Carrying	Level	Level	Level		Carrying	Level	Level	Level
	Amount	1	2	3	Total	Amount	1	2	3	Total
Assets:
Commodity derivatives	$44	$—	$35	$9	$44	$99	$—	$95	$4	$99
Liabilities:
Commodity derivatives	45	—	44	1	45	33	—	32	1	33
Long-term debt	3,069	—	2,722	—	2,722	2,770	—	2,542	—	2,542

Fair Value Measurements Using Significant Unobservable Inputs

Information for fair value measurements using significant unobservable inputs (Level 3 inputs) was as follows (in millions):

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$54	$72	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	17	(1)	—	—
Sales	(1)	—	—	—
Settlements (a)	(27)	(26)	61	4
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$17	($1)	$—	$—

Alliant Energy	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$19	$29	$185	$214
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(17)	—	—
Purchases	62	79	—	—
Sales	(2)	—	—	—
Settlements (a)	(42)	(46)	51	34
Ending balance, September 30	$43	$45	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($17)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Three Months Ended September 30	2023	2022	2023	2022
Beginning balance, July 1	$41	$58	$175	$244
Total net gains (losses) included in changes in net assets (realized/unrealized)	12	(6)	—	—
Sales	(1)	—	—	—
Settlements (a)	(17)	(19)	61	4
Ending balance, September 30	$35	$33	$236	$248
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$12	($6)	$—	$—

IPL	Commodity Contract Derivative
	Assets and (Liabilities), net		Deferred Proceeds
Nine Months Ended September 30	2023	2022	2023	2022
Beginning balance, January 1	$16	$18	$185	$214
Total net losses included in changes in net assets (realized/unrealized)	—	(13)	—	—
Purchases	51	58	—	—
Sales	(2)	—	—	—
Settlements (a)	(30)	(30)	51	34
Ending balance, September 30	$35	$33	$236	$248
The amount of total net losses for the period included in changes in net assets attributable to the change in unrealized losses relating to assets and liabilities held at September 30	$—	($14)	$—	$—

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Three Months Ended September 30	2023	2022
Beginning balance, July 1	$13	$14
Total net gains included in changes in net assets (realized/unrealized)	5	5
Settlements	(10)	(7)
Ending balance, September 30	$8	$12
The amount of total net gains for the period included in changes in net assets attributable to the change in unrealized gains relating to assets and liabilities held at September 30	$5	$5

WPL	Commodity Contract Derivative
	Assets and (Liabilities), net
Nine Months Ended September 30	2023	2022
Beginning balance, January 1	$3	$11
Total net gains (losses) included in changes in net assets (realized/unrealized)	6	(4)
Purchases	11	21
Settlements	(12)	(16)
Ending balance, September 30	$8	$12
The amount of total net gains (losses) for the period included in changes in net assets attributable to the change in unrealized gains (losses) relating to assets and liabilities held at September 30	$6	($3)

(a)Settlements related to deferred proceeds are due to the change in the carrying amount of receivables sold less the allowance for expected credit losses associated with the receivables sold and cash amounts received from the receivables sold.

Fair Value Of Net Derivative Assets (Liabilities)

The fair value of FTR and natural gas commodity contracts categorized as Level 3 was recognized as net derivative assets (liabilities) as follows (in millions):

	Alliant Energy		IPL		WPL
	Excluding FTRs	FTRs	Excluding FTRs	FTRs	Excluding FTRs	FTRs
September 30, 2023	$3	$40	$4	$31	($1)	$9
December 31, 2022	(10)	29	(9)	25	(1)	4