v3.25.2
Debt (Tables)
 6 Months Ended
Jun. 30, 2025
Short-term Debt [Line Items]  
Schedule of Other Short-term Borrowings Information regarding commercial paper and borrowings under the single credit facility classified as short-term debt was as follows (dollars in millions):
June 30, 2025Alliant EnergyIPLWPL
Amount outstanding$292$—$292
Weighted average interest rates4.6%N/A4.6%
Available credit facility capacity$1,008$350$108
Alliant EnergyIPLWPL
Three Months Ended June 30202520242025202420252024
Maximum amount outstanding (based on daily outstanding balances)$741$435$141$19$292$57
Average amount outstanding (based on daily outstanding balances)$449$275$33$2$225$8
Weighted average interest rates4.6%5.5%4.6%5.5%4.6%5.4%
Six Months Ended June 30
Maximum amount outstanding (based on daily outstanding balances)$741$632$141$19$292$390
Average amount outstanding (based on daily outstanding balances)$495$381$43$1$193$131
Weighted average interest rates4.6%5.5%4.6%5.5%4.6%5.5%
IPL [Member]  
Short-term Debt [Line Items]  
Schedule of Other Short-term Borrowings Information regarding commercial paper and borrowings under the single credit facility classified as short-term debt was as follows (dollars in millions):
June 30, 2025Alliant EnergyIPLWPL
Amount outstanding$292$—$292
Weighted average interest rates4.6%N/A4.6%
Available credit facility capacity$1,008$350$108
Alliant EnergyIPLWPL
Three Months Ended June 30202520242025202420252024
Maximum amount outstanding (based on daily outstanding balances)$741$435$141$19$292$57
Average amount outstanding (based on daily outstanding balances)$449$275$33$2$225$8
Weighted average interest rates4.6%5.5%4.6%5.5%4.6%5.4%
Six Months Ended June 30
Maximum amount outstanding (based on daily outstanding balances)$741$632$141$19$292$390
Average amount outstanding (based on daily outstanding balances)$495$381$43$1$193$131
Weighted average interest rates4.6%5.5%4.6%5.5%4.6%5.5%
WPL [Member]  
Short-term Debt [Line Items]  
Schedule of Other Short-term Borrowings Information regarding commercial paper and borrowings under the single credit facility classified as short-term debt was as follows (dollars in millions):
June 30, 2025Alliant EnergyIPLWPL
Amount outstanding$292$—$292
Weighted average interest rates4.6%N/A4.6%
Available credit facility capacity$1,008$350$108
Alliant EnergyIPLWPL
Three Months Ended June 30202520242025202420252024
Maximum amount outstanding (based on daily outstanding balances)$741$435$141$19$292$57
Average amount outstanding (based on daily outstanding balances)$449$275$33$2$225$8
Weighted average interest rates4.6%5.5%4.6%5.5%4.6%5.4%
Six Months Ended June 30
Maximum amount outstanding (based on daily outstanding balances)$741$632$141$19$292$390
Average amount outstanding (based on daily outstanding balances)$495$381$43$1$193$131
Weighted average interest rates4.6%5.5%4.6%5.5%4.6%5.5%