Conversion Amount Of Principal Amount

No definition available.

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- Definition

Conversion Price Percentage Fundamental Change Repurchase

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

Threshold Percentage of Stock Price and Conversion Rate

+ References

No definition available.

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- Definition

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.

+ References

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- Definition

The price per share of the conversion feature embedded in the debt instrument.

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- Definition

Ratio applied to the conversion of debt instrument into equity with equity shares divided by debt principal amount.

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- Definition

Threshold period of specified consecutive trading days within which common stock price to conversion price of convertible debt instrument must exceed threshold percentage for specified number of trading days to trigger conversion feature.

+ References

No definition available.

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- Definition

Minimum percentage of common stock price to conversion price of convertible debt instruments to determine eligibility of conversion.

+ References

No definition available.

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- Definition

Threshold number of specified trading days that common stock price to conversion price of convertible debt instruments must exceed threshold percentage within a specified consecutive trading period to trigger conversion feature.

+ References

No definition available.

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- Definition

Contractual interest rate for funds borrowed, under the debt agreement.

+ References

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- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

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- Definition

Amount of current borrowing capacity under the credit facility considering any current restrictions on the amount that could be borrowed (for example, borrowings may be limited by the amount of current assets), but without considering any amounts currently outstanding under the facility.

+ References

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Amount, after deduction of unamortized premium (discount) and debt issuance cost, of long-term debt. Excludes lease obligation.

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The fair value amount of long-term debt whether such amount is presented as a separate caption or as a parenthetical disclosure. Additionally, this element may be used in connection with the fair value disclosures required in the footnote disclosures to the financial statements. The element may be used in both the balance sheet and disclosure in the same submission.

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The cash outflow for debt initially having maturity due after one year or beyond the normal operating cycle, if longer.

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The remaining balance of debt issuance expenses that were capitalized and are being amortized against income over the lives of the respective bond issues. This does not include the amounts capitalized as part of the cost of the utility plant or asset.

+ References

No definition available.

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The sum of dilutive potential common shares or units used in the calculation of the diluted per-share or per-unit computation.

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Debt (Narrative) (Details)	6 Months Ended
Debt (Narrative) (Details)	Jun. 30, 2025 USD ($) Integer $ / shares shares	Jun. 30, 2024 USD ($)	Mar. 31, 2026 USD ($)	Dec. 31, 2024 USD ($)
Debt [Line Items]
Line of credit facility, current borrowing capacity	$ 1,300,000,000
Payments to retire long-term debt	0	$ 305,000,000
Long-term debt, fair value	10,617,000,000			$ 9,577,000,000
Parent Company [Member]
Debt [Line Items]
Line of credit facility, current borrowing capacity	550,000,000
IPL [Member]
Debt [Line Items]
Line of credit facility, current borrowing capacity	350,000,000
Long-term debt, fair value	4,408,000,000			3,736,000,000
WPL [Member]
Debt [Line Items]
Line of credit facility, current borrowing capacity	400,000,000
Long-term debt, fair value	3,238,000,000			$ 3,170,000,000
Term Loan Credit Agreement [Member] \| Term loan credit agreement through March 2026 [Member] \| Alliant Energy Finance LLC [Member]
Debt [Line Items]
Long-term debt	$ 300,000,000
Interest rate, percent	5.00%
Term Loan Credit Agreement [Member] \| Term loan credit agreement through March 2026 [Member] \| Alliant Energy Finance LLC [Member] \| Forecast [Member]
Debt [Line Items]
Long-term debt			$ 100,000,000
Term Loan Credit Agreement [Member] \| Term loan credit agreement through March 2025 [Member] \| Alliant Energy Finance LLC [Member]
Debt [Line Items]
Payments to retire long-term debt	$ 300,000,000
Senior Debentures [Member] \| 5.6% senior debentures, due 2035 [Member] \| IPL [Member]
Debt [Line Items]
Long-term debt	$ 600,000,000
Interest rate, percent	5.60%
Senior Debentures [Member] \| 5.5% senior debentures, due 2025 [Member] \| IPL [Member]
Debt [Line Items]
Long-term debt	$ 50,000,000
Interest rate, percent	5.50%
Senior Debentures [Member] \| 3.4% senior debentures, due 2025 [Member] \| IPL [Member]
Debt [Line Items]
Long-term debt	$ 250,000,000
Interest rate, percent	3.40%
Convertible Senior Notes [Member]
Debt [Line Items]
Trading days \| Integer	20
Trading days consecutive \| Integer	30
Convertible Senior Notes [Member] \| 3.25% convertible senior notes, due 2028 [Member]
Debt [Line Items]
Long-term debt	$ 575,000,000
Interest rate, percent	3.25%
Trading days \| Integer	5
Trading days consecutive \| Integer	10
Principal amount of Notes conversion rate applied to	$ 1,000
Initial conversion ratio (in shares)	13.1773
Initial conversion price (in dollars per share) \| $ / shares	$ 75.89
Fundamental change repurchase conversion price, percent	100.00%
Long-term debt, carrying value	$ 568,000,000
Unamortized debt issuance costs	7,000,000
Long-term debt, fair value	$ 574,000,000
Shares included in diluted earnings per share (in shares) \| shares	0
Convertible Senior Notes [Member] \| 3.25% convertible senior notes, due 2028 [Member] \| Maximum [Member]
Debt [Line Items]
Conversion price, percent	130.00%
Threshold, product of last reported sale price of common stock and conversion rate, percent	98.00%
Convertible Senior Notes [Member] \| 3.875% convertible senior notes, due 2026 [Member]
Debt [Line Items]
Long-term debt, carrying value	$ 573,000,000
Unamortized debt issuance costs	2,000,000
Long-term debt, fair value	$ 592,000,000
Shares included in diluted earnings per share (in shares) \| shares	0