Benefit Plans (Assumptions Used To Measure Benefit Plans) (Details)	12 Months Ended
	Dec. 31, 2022	Dec. 31, 2021	Dec. 31, 2020
Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligations	5.54%	2.91%	2.57%
Discount rate for net periodic cost	2.91%	2.57%	3.48%
Expected rate of return on plan assets	7.80%	7.10%	7.10%
Interest crediting rate for Alliant Energy Cash Balance Pension Plan	9.22%	4.18%	4.76%
Pension Plans, Defined Benefit [Member] | IPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligations	5.55%	2.94%	2.61%
Discount rate for net periodic cost	2.94%	2.61%	3.51%
Expected rate of return on plan assets	7.80%	7.10%	7.10%
Rate of compensation increase	3.30%	3.30%	3.65%
Pension Plans, Defined Benefit [Member] | WPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligations	5.54%	2.94%	2.64%
Discount rate for net periodic cost	2.94%	2.64%	3.50%
Expected rate of return on plan assets	7.80%	7.10%	7.10%
Rate of compensation increase	3.30%	3.30%	3.65%
Other Postretirement Benefits Plans [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligations	5.53%	2.81%	2.31%
Discount rate for net periodic cost	2.81%	2.31%	3.40%
Expected rate of return on plan assets	6.40%	4.80%	4.50%
Other Postretirement Benefits Plans [Member] | IPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligations	5.53%	2.80%	2.28%
Discount rate for net periodic cost	2.80%	2.28%	3.39%
Expected rate of return on plan assets	6.50%	5.10%	4.50%
Other Postretirement Benefits Plans [Member] | WPL [Member]
Defined Benefit Plan Disclosure [Line Items]
Discount rate for benefit obligations	5.53%	2.79%	2.27%
Discount rate for net periodic cost	2.79%	2.27%	3.39%
Expected rate of return on plan assets	5.49%	4.02%	3.28%
Minimum [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase	3.30%	3.30%	3.65%
Maximum [Member] | Pension Plans, Defined Benefit [Member]
Defined Benefit Plan Disclosure [Line Items]
Rate of compensation increase	4.50%	4.50%	4.50%