Income Taxes (Summary Of Tax Credit Carryforwards) (Details) $ in Millions	Jun. 30, 2022 USD ($)
Federal [Member]
Carryforwards [Line Items]
Net operating losses, carryforward amount	$ 41
Tax credits, carryforward amount	620
State [Member]
Carryforwards [Line Items]
Net operating losses, carryforward amount	556
IPL [Member] | Federal [Member]
Carryforwards [Line Items]
Net operating losses, carryforward amount	38
Tax credits, carryforward amount	396
IPL [Member] | State [Member]
Carryforwards [Line Items]
Net operating losses, carryforward amount	10
WPL [Member] | Federal [Member]
Carryforwards [Line Items]
Net operating losses, carryforward amount	0
Tax credits, carryforward amount	201
WPL [Member] | State [Member]
Carryforwards [Line Items]
Net operating losses, carryforward amount	$ 2