Benefit Plans (Assumptions Used To Measure Benefit Plans) (Details)	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligations	5.36%	5.54%	2.91%
Discount rate for net periodic cost	5.54%	2.91%	2.57%
Expected rate of return on plan assets	7.80%	7.80%	7.10%
Interest crediting rate for Alliant Energy Cash Balance Pension Plan	10.75%	9.22%	4.18%
Pension Plans, Defined Benefit [Member] | IPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligations	5.35%	5.55%	2.94%
Discount rate for net periodic cost	5.55%	2.94%	2.61%
Expected rate of return on plan assets	7.80%	7.80%	7.10%
Rate of compensation increase	3.30%	3.30%	3.30%
Pension Plans, Defined Benefit [Member] | WPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligations	5.35%	5.54%	2.94%
Discount rate for net periodic cost	5.54%	2.94%	2.64%
Expected rate of return on plan assets	7.80%	7.80%	7.10%
Rate of compensation increase	3.30%	3.30%	3.30%
Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligations	5.40%	5.53%	2.81%
Discount rate for net periodic cost	5.53%	2.81%	2.31%
Expected rate of return on plan assets	6.50%	6.40%	4.80%
Other Postretirement Benefits Plans [Member] | IPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligations	5.40%	5.53%	2.80%
Discount rate for net periodic cost	5.53%	2.80%	2.28%
Expected rate of return on plan assets	6.90%	6.50%	5.10%
Other Postretirement Benefits Plans [Member] | WPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligations	5.40%	5.53%	2.79%
Discount rate for net periodic cost	5.53%	2.79%	2.27%
Expected rate of return on plan assets	5.65%	5.49%	4.02%
Minimum [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase	3.30%	3.30%	3.30%
Maximum [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase	4.50%	4.50%	4.50%