Income Taxes (Summary Of Tax Credit Carryforwards) (Details) $ in Millions	Dec. 31, 2021 USD ($)
Federal [Member]
Tax carryforwards, net operating losses	$ 186
Tax carryforwards, tax credits	560
Federal [Member] | IPL [Member]
Tax carryforwards, net operating losses	172
Tax carryforwards, tax credits	345
Federal [Member] | WPL [Member]
Tax carryforwards, net operating losses	1
Tax carryforwards, tax credits	192
State [Member]
Tax carryforwards, net operating losses	619
State [Member] | IPL [Member]
Tax carryforwards, net operating losses	28
State [Member] | WPL [Member]
Tax carryforwards, net operating losses	$ 2