Commitments And Contingencies (Other Purchase Obligations) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2018 USD ($)
Commitments and Contingencies [Line Items]
Minimum future commitments	$ 2,278
Individual commitments incurred	1
IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	1,603
Individual commitments incurred	1
WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	661
Individual commitments incurred	1
Purchased Power [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	1,175	[1]
Purchased Power [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	1,127	[1]
Purchased Power [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	48	[1]
Natural gas [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	892
Natural gas [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	362
Natural gas [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	530
Coal [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	165	[2]
Coal [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	88	[2]
Coal [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	77	[2]
Other [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	46	[3]
Other [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	26	[3]
Other [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	$ 6	[3]

[1] Includes payments required by purchased power agreements for capacity rights and minimum quantities of MWhs required to be purchased.

[2] Corporate Services entered into system-wide coal contracts on behalf of IPL and WPL that include minimum future commitments. These commitments were assigned to IPL and WPL based on information available as of March 31, 2018 regarding expected future usage, which is subject to change.

[3] Includes individual commitments incurred during the normal course of business that exceeded $1 million at March 31, 2018.