Debt (Schedule Of Debt-To-Capital Ratios) (Details)	Dec. 31, 2015
Actual	50.00%
IPL [Member]
Actual	46.00%
WPL [Member]
Actual	48.00%
Maximum [Member]
Requirement, not to exceed	65.00%
Maximum [Member] | IPL [Member]
Requirement, not to exceed	58.00%
Maximum [Member] | WPL [Member]
Requirement, not to exceed	58.00%