Amount, before unamortized (discount) premium and debt issuance costs, of long-term debt. Includes, but is not limited to, notes payable, bonds payable, commercial loans, mortgage loans, convertible debt, subordinated debt and other types of debt.

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Amount, after unamortized (discount) premium and debt issuance costs, of long-term debt, classified as current. Includes, but not limited to, notes payable, bonds payable, debentures, mortgage loans and commercial paper. Excludes capital lease obligations.

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Debt (Long-term Debt) (Details) - USD ($) $ in Millions	1 Months Ended	12 Months Ended
Debt (Long-term Debt) (Details) - USD ($) $ in Millions	Dec. 31, 2022	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020	Mar. 31, 2022
Debt Instrument [Line Items]
Long-term debt	$ 8,143	$ 8,143	$ 7,425
Current maturities	(408)	(408)	(633)
Unamortized debt issuance costs	(45)	(45)	(42)
Unamortized debt (discount) and premium, net	(22)	(22)	(15)
Long-term debt, net	7,668	7,668	6,735
Proceeds from issuance of long-term debt		1,338	600	$ 1,250
Senior Debentures [Member]
Debt Instrument [Line Items]
Long-term debt	3,675	3,675	3,675
Senior Debentures [Member] \| 3.25% senior debenture, due 2024 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 500	$ 500	$ 500
Interest rate	3.25%	3.25%	3.25%
Senior Debentures [Member] \| 3.4% senior debenture, due 2025 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 250	$ 250	$ 250
Interest rate	3.40%	3.40%	3.40%
Senior Debentures [Member] \| 5.5% senior debenture, due 2025 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 50	$ 50	$ 50
Interest rate	5.50%	5.50%	5.50%
Senior Debentures [Member] \| 4.1% senior debenture, due 2028 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 500	$ 500	$ 500
Interest rate	4.10%	4.10%	4.10%
Senior Debentures [Member] \| 3.6% senior debenture, due 2029 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	3.60%	3.60%	3.60%
Senior Debentures [Member] \| 2.3% senior debenture, due 2030 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 400	$ 400	$ 400
Interest rate	2.30%	2.30%	2.30%
Senior Debentures [Member] \| 6.45% senior debenture, due 2033 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 100	$ 100	$ 100
Interest rate	6.45%	6.45%	6.45%
Senior Debentures [Member] \| 6.3% senior debenture, due 2034 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 125	$ 125	$ 125
Interest rate	6.30%	6.30%	6.30%
Senior Debentures [Member] \| 6.25% senior debenture, due 2039 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	6.25%	6.25%	6.25%
Senior Debentures [Member] \| 4.7% senior debenture, due 2043 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 250	$ 250	$ 250
Interest rate	4.70%	4.70%	4.70%
Senior Debentures [Member] \| 3.7% senior debenture, due 2046 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	3.70%	3.70%	3.70%
Senior Debentures [Member] \| 3.5% senior debenture, due 2049 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	3.50%	3.50%	3.50%
Senior Debentures [Member] \| 3.1% senior debenture, due 2051 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	3.10%	3.10%	3.10%
Debentures [Member]
Debt Instrument [Line Items]
Long-term debt	$ 2,800	$ 2,800	$ 2,450
Debentures [Member] \| 3.05% debenture, due 2027 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	3.05%	3.05%	3.05%
Debentures [Member] \| 3% debenture, due 2029 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 350	$ 350	$ 350
Interest rate	3.00%	3.00%	3.00%
Debentures [Member] \| 1.95% debenture, due 2031 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	1.95%	1.95%	1.95%
Debentures [Member] \| 3.95% debenture, due 2032 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 600	$ 600	$ 0
Interest rate	3.95%	3.95%
Debentures [Member] \| 6.25% debenture, due 2034 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 100	$ 100	$ 100
Interest rate	6.25%	6.25%	6.25%
Debentures [Member] \| 6.375% debenture, due 2037 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	6.375%	6.375%	6.375%
Debentures [Member] \| 7.6% debenture, due 2038 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 250	$ 250	$ 250
Interest rate	7.60%	7.60%	7.60%
Debentures [Member] \| 4.1% debenture, due 2044 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 250	$ 250	$ 250
Interest rate	4.10%	4.10%	4.10%
Debentures [Member] \| 3.65% debenture, due 2050 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 350	$ 350	$ 350
Interest rate	3.65%	3.65%	3.65%
Debentures [Member] \| 2.25% debenture, due 2022 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 0	$ 0	$ 250
Interest rate			2.25%
Other Long Term Debt [Member]
Debt Instrument [Line Items]
Long-term debt	1,668	1,668	$ 1,300
Other [Member] \| Other, 1% at December 31, 2022, due 2023 to 2025 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 1	$ 1	1
Interest rate	1.00%	1.00%
IPL [Member]
Debt Instrument [Line Items]
Long-term debt	$ 3,675	$ 3,675	3,675
Current maturities	0	0	0
Unamortized debt issuance costs	(21)	(21)	(23)
Unamortized debt (discount) and premium, net	(8)	(8)	(9)
Long-term debt, net	3,646	3,646	3,643
Proceeds from issuance of long-term debt		0	300	400
IPL [Member] \| Senior Debentures [Member]
Debt Instrument [Line Items]
Long-term debt	3,675	3,675	3,675
IPL [Member] \| Senior Debentures [Member] \| 3.25% senior debenture, due 2024 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 500	$ 500	$ 500
Interest rate	3.25%	3.25%	3.25%
IPL [Member] \| Senior Debentures [Member] \| 3.4% senior debenture, due 2025 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 250	$ 250	$ 250
Interest rate	3.40%	3.40%	3.40%
IPL [Member] \| Senior Debentures [Member] \| 5.5% senior debenture, due 2025 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 50	$ 50	$ 50
Interest rate	5.50%	5.50%	5.50%
IPL [Member] \| Senior Debentures [Member] \| 4.1% senior debenture, due 2028 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 500	$ 500	$ 500
Interest rate	4.10%	4.10%	4.10%
IPL [Member] \| Senior Debentures [Member] \| 3.6% senior debenture, due 2029 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	3.60%	3.60%	3.60%
IPL [Member] \| Senior Debentures [Member] \| 2.3% senior debenture, due 2030 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 400	$ 400	$ 400
Interest rate	2.30%	2.30%	2.30%
IPL [Member] \| Senior Debentures [Member] \| 6.45% senior debenture, due 2033 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 100	$ 100	$ 100
Interest rate	6.45%	6.45%	6.45%
IPL [Member] \| Senior Debentures [Member] \| 6.3% senior debenture, due 2034 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 125	$ 125	$ 125
Interest rate	6.30%	6.30%	6.30%
IPL [Member] \| Senior Debentures [Member] \| 6.25% senior debenture, due 2039 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	6.25%	6.25%	6.25%
IPL [Member] \| Senior Debentures [Member] \| 4.7% senior debenture, due 2043 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 250	$ 250	$ 250
Interest rate	4.70%	4.70%	4.70%
IPL [Member] \| Senior Debentures [Member] \| 3.7% senior debenture, due 2046 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	3.70%	3.70%	3.70%
IPL [Member] \| Senior Debentures [Member] \| 3.5% senior debenture, due 2049 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	3.50%	3.50%	3.50%
IPL [Member] \| Senior Debentures [Member] \| 3.1% senior debenture, due 2051 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	3.10%	3.10%	3.10%
WPL [Member]
Debt Instrument [Line Items]
Long-term debt	$ 2,800	$ 2,800	$ 2,450
Current maturities	0	0	(250)
Unamortized debt issuance costs	(19)	(19)	(15)
Unamortized debt (discount) and premium, net	(11)	(11)	(6)
Long-term debt, net	2,770	2,770	2,179
Proceeds from issuance of long-term debt		588	300	$ 350
WPL [Member] \| Debentures [Member]
Debt Instrument [Line Items]
Long-term debt	2,800	2,800	2,450
WPL [Member] \| Debentures [Member] \| 3.05% debenture, due 2027 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	3.05%	3.05%	3.05%
WPL [Member] \| Debentures [Member] \| 3% debenture, due 2029 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 350	$ 350	$ 350
Interest rate	3.00%	3.00%	3.00%
WPL [Member] \| Debentures [Member] \| 1.95% debenture, due 2031 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	1.95%	1.95%	1.95%
WPL [Member] \| Debentures [Member] \| 3.95% debenture, due 2032 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 600	$ 600	$ 0
Interest rate	3.95%	3.95%
WPL [Member] \| Debentures [Member] \| 6.25% debenture, due 2034 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 100	$ 100	$ 100
Interest rate	6.25%	6.25%	6.25%
WPL [Member] \| Debentures [Member] \| 6.375% debenture, due 2037 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	6.375%	6.375%	6.375%
WPL [Member] \| Debentures [Member] \| 7.6% debenture, due 2038 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 250	$ 250	$ 250
Interest rate	7.60%	7.60%	7.60%
WPL [Member] \| Debentures [Member] \| 4.1% debenture, due 2044 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 250	$ 250	$ 250
Interest rate	4.10%	4.10%	4.10%
WPL [Member] \| Debentures [Member] \| 3.65% debenture, due 2050 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 350	$ 350	$ 350
Interest rate	3.65%	3.65%	3.65%
WPL [Member] \| Debentures [Member] \| 2.25% debenture, due 2022 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 0	$ 0	$ 250
Interest rate			2.25%
Alliant Energy Finance, LLC [Member] \| Senior Notes [Member] \| 3.75% senior notes, due 2023 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 400	$ 400	$ 400
Interest rate	3.75%	3.75%	3.75%
Alliant Energy Finance, LLC [Member] \| Senior Notes [Member] \| 1.4% senior notes, due 2026 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 200	$ 200	$ 200
Interest rate	1.40%	1.40%	1.40%
Alliant Energy Finance, LLC [Member] \| Senior Notes [Member] \| 4.25% senior notes, due 2028 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 300	$ 300	$ 300
Interest rate	4.25%	4.25%	4.25%
Alliant Energy Finance, LLC [Member] \| Senior Notes [Member] \| 3.6% senior notes, due 2032 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 350	$ 350	$ 0
Interest rate	3.60%	3.60%
Alliant Energy Finance, LLC [Member] \| Term Loan Credit Agreement [Member] \| Term loan credit agreement through March 2024, Variable Rate [Member]
Debt Instrument [Line Items]
Long-term debt	$ 400	$ 400	0		$ 300
Interest rate	5.00%	5.00%
Proceeds from issuance of long-term debt	$ 100
Alliant Energy Finance, LLC [Member] \| Term Loan Credit Agreement [Member] \| Term loan credit agreement through March 2022 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 0	$ 0	$ 300
Interest rate			1.00%
Alliant Energy Finance, LLC [Member] \| Term Loan Credit Agreement [Member] \| Term loan credit agreement through March 2024, Fixed Rate [Member]
Debt Instrument [Line Items]
Interest rate	3.93%	3.93%
Sheboygan Power, LLC [Member] \| Senior Secured Notes [Member] \| 5.06% senior secured notes, due 2023 to 2024 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 17	$ 17	$ 24
Interest rate	5.06%	5.06%	5.06%
Corporate Services [Member] \| Senior Notes [Member] \| 3.45% senior notes, due 2022 [Member]
Debt Instrument [Line Items]
Long-term debt	$ 0	$ 0	$ 75
Interest rate			3.45%