Commitments And Contingencies (Operating Expense Purchase Obligations) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2017 USD ($)
Commitments and Contingencies [Line Items]
Minimum future commitments	$ 2,387
Individual commitments incurred	1
IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	1,785
Individual commitments incurred	1
WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	587
Individual commitments incurred	1
Purchased power [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	1,372	[1]
Purchased power [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	1,266	[1]
Purchased power [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	106	[1]
Natural gas [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	812
Natural gas [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	426
Natural gas [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	386
Coal [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	165	[2]
Coal [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	73	[2]
Coal [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	92	[2]
Other [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	38	[3]
Other [Member] | IPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	20	[3]
Other [Member] | WPL [Member]
Commitments and Contingencies [Line Items]
Minimum future commitments	$ 3	[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, 2017 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, 2017.