Summary Of Significant Accounting Policies (Narrative) (Details) $ in Millions	12 Months Ended
	Dec. 31, 2023 USD ($) customer MW	Dec. 31, 2022 USD ($)
Cash, Cash Equivalents and Restricted Cash:
Money market fund investments | $	$ 45	$ 10
Money market fund investments interest rate, percentage	5.00%
Non-utility wind farm in Oklahoma [Member]
General:
Ownership interest	50.00%
IPL [Member]
General:
Generation and distribution of steam, number of customers served (in customers) | customer	2
Cash, Cash Equivalents and Restricted Cash:
Money market fund investments | $	$ 45	$ 10
Money market fund investments interest rate, percentage	5.00%
Property, Plant and Equipment:
AFUDC accrual recorded, percentage of estimated CWIP	100.00%
WPL [Member]
Property, Plant and Equipment:
AFUDC accrual recorded, percentage of estimated CWIP	50.00%
AFUDC accrual recorded, percentage earning a return as part of rate base	50.00%
AFUDC rates, projects with approval	100.00%
Alliant Energy Finance, LLC [Member]
General:
Electric capacity of wind farm (in megawatts) | MW	225
Alliant Energy Finance, LLC [Member] | Non-utility wind farm in Oklahoma [Member]
General:
Ownership interest	50.00%
Sheboygan Falls Energy Facility [Member]
General:
Fossil-fueled EGU capacity (in megawatts) | MW	347