Summary Of Significant Accounting Policies (Narrative) (Details) $ in Millions	3 Months Ended		12 Months Ended
	Sep. 30, 2022 USD ($)	Jun. 30, 2022 USD ($)	Dec. 31, 2024 MWd	Dec. 31, 2023	Dec. 31, 2022 USD ($) customer MW	Dec. 31, 2021 USD ($)	Dec. 31, 2020 USD ($)	Dec. 31, 2019 USD ($)
Current Expected Credit Losses Estimates:
New accounting standard, cumulative effect adjustment to retained earnings, after-tax					$ (3,509)	$ (3,250)
Variable Interest Entities
Distributions to noncontrolling interest					$ 29	0	$ 0
Non-utility wind farm in Oklahoma [Member]
General:
Ownership interest					50.00%
Cumulative Effect, Period of Adoption, Adjustment [Member]
Current Expected Credit Losses Estimates:
New accounting standard, cumulative effect adjustment to retained earnings, pre-tax							12
New accounting standard, cumulative effect adjustment to retained earnings, after-tax							9	$ 9
IPL [Member]
General:
Generation and distribution of steam, number of customers served (in customers) | customer					2
Electric capacity of wind farm (in megawatts) | MW					1,000
Property, Plant and Equipment:
AFUDC accrual recorded, percentage of estimated CWIP					100.00%
Current Expected Credit Losses Estimates:
New accounting standard, cumulative effect adjustment to retained earnings, after-tax					$ (968)	(929)
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%
Current Expected Credit Losses Estimates:
New accounting standard, cumulative effect adjustment to retained earnings, after-tax					$ (1,192)	(1,053)
Variable Interest Entities
WPL's cash contribution		$ 62
Tax equity partner's cash contribution		29
Contributed funds paid to WPL for equity interests		$ 88
Distributions to noncontrolling interest	$ 29				$ 29	$ 0	$ 0
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
Finance lease, lease term					20 years
Electric Generation Equipment [Member] | IPL [Member]
Property, Plant and Equipment:
Average rate of depreciation					3.40%	3.40%	3.50%
Electric Generation Equipment [Member] | WPL [Member]
Property, Plant and Equipment:
Average rate of depreciation					3.40%	3.50%	3.50%
Distribution [Member] | IPL [Member]
Property, Plant and Equipment:
Average rate of depreciation					2.80%	2.90%	2.80%
Distribution [Member] | WPL [Member]
Property, Plant and Equipment:
Average rate of depreciation					2.50%	2.60%	2.60%
Gas [Member] | IPL [Member]
Property, Plant and Equipment:
Average rate of depreciation					3.30%	3.30%	3.30%
Gas [Member] | WPL [Member]
Property, Plant and Equipment:
Average rate of depreciation					2.40%	2.40%	2.40%
Forecast [Member] | Solar [Member] | WPL [Member]
Variable Interest Entities
Nameplate capacity (in MWs) | MWd			1,100
Forecast [Member] | Electric Generation Equipment [Member] | WPL [Member]
Property, Plant and Equipment:
Average rate of depreciation				3.60%
Forecast [Member] | Distribution [Member] | WPL [Member]
Property, Plant and Equipment:
Average rate of depreciation				2.70%
Forecast [Member] | Gas [Member] | WPL [Member]
Property, Plant and Equipment:
Average rate of depreciation				2.90%