Debt (Narrative) (Details)	12 Months Ended
	Dec. 31, 2023 USD ($) Integer $ / shares shares	Dec. 31, 2024 USD ($)	Dec. 31, 2022 USD ($)
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity	$ 1,000,000,000
Long-term debt	9,109,000,000		$ 8,143,000,000
Long-term debt, fair value	$ 8,677,000,000		7,339,000,000
Subsequent Event
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity		$ 350,000,000
Convertible Debt
Debt Instrument [Line Items]
Trading days | Integer	20
Trading days consecutive | Integer	30
3.875% senior notes, due 2026 [Member] | Convertible Debt
Debt Instrument [Line Items]
Long-term debt	$ 575,000,000
Interest rate, percent	3.875%
Trading days | Integer	5
Trading days consecutive | Integer	10
Principal amount of Notes conversion rate applied to	$ 1,000
Initial conversion ratio	15.5461
Initial conversion price | $ / shares	$ 64.32
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	$ 572,000,000
Shares included in diluted earnings per share (in shares) | shares	0
3.875% senior notes, due 2026 [Member] | Convertible Debt | Maximum [Member]
Debt Instrument [Line Items]
Conversion price, percent	130.00%
Parent Company [Member]
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity	$ 450,000,000
IPL [Member]
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity	150,000,000
Long-term debt	3,975,000,000		3,675,000,000
Long-term debt, fair value	3,664,000,000		3,228,000,000
IPL [Member] | Subsequent Event
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity		150,000,000
WPL [Member]
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity	400,000,000
Long-term debt	3,100,000,000		2,800,000,000
Long-term debt, fair value	$ 2,933,000,000		$ 2,542,000,000
WPL [Member] | Subsequent Event
Debt Instrument [Line Items]
Line of credit facility, current borrowing capacity		500,000,000
Forecast [Member] | Parent Company [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		500,000,000
Forecast [Member] | IPL [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		400,000,000
Forecast [Member] | WPL [Member]
Debt Instrument [Line Items]
Line of credit facility, maximum borrowing capacity		$ 500,000,000