Commitments And Contingencies (Other Purchase Commitments) (Details) $ in Millions	6 Months Ended
	Jun. 30, 2025 USD ($)
Commitments and Contingencies [Line Items]
Minimum future commitments	$ 1,038
Individual commitments incurred	1
IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	553
Individual commitments incurred	1
WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	450
Individual commitments incurred	1
Natural gas [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	783
Natural gas [Member] \| IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	439
Natural gas [Member] \| WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	344
Coal [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	138
Coal [Member] \| IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	61
Coal [Member] \| WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	77
Other [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	117
Other [Member] \| IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	53
Other [Member] \| WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	$ 29

ALLIANT ENERGY CORP 10-Q