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Income Taxes (Schedule Of Effective Income Tax Rates) (Details)	3 Months Ended		6 Months Ended
	Jun. 30, 2017	Jun. 30, 2016	Jun. 30, 2017	Jun. 30, 2016
Effective Tax Rate [Line Items]
Statutory federal income tax rate	35.00%	35.00%	35.00%	35.00%
Effect of rate-making on property-related differences	(9.00%)	(4.90%)	(8.00%)	(5.90%)
IPL's tax benefit riders	(7.80%)	(7.90%)	(7.80%)	(8.40%)
Production tax credits	(5.90%)	(5.70%)	(5.90%)	(6.00%)
Other items, net	5.70%	0.70%	3.10%	2.80%
Overall income tax rate	18.00%	17.20%	16.40%	17.50%
IPL [Member]
Effective Tax Rate [Line Items]
Statutory federal income tax rate	35.00%	35.00%	35.00%	35.00%
Effect of rate-making on property-related differences	(18.00%)	(8.80%)	(18.00%)	(12.50%)
IPL's tax benefit riders	(18.60%)	(16.60%)	(19.00%)	(19.00%)
Production tax credits	(6.20%)	(5.30%)	(6.40%)	(6.10%)
Other items, net	6.50%	(2.00%)	3.10%	2.60%
Overall income tax rate	(1.30%)	2.30%	(5.30%)	0.00%
WPL [Member]
Effective Tax Rate [Line Items]
Statutory federal income tax rate	35.00%	35.00%	35.00%	35.00%
Effect of rate-making on property-related differences	(1.90%)	(1.00%)	(1.80%)	(0.90%)
Production tax credits	(7.10%)	(6.30%)	(7.00%)	(6.40%)
Other items, net	4.50%	4.50%	4.50%	4.70%
Overall income tax rate	30.50%	32.20%	30.70%	32.40%

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Percentage of current income tax expense (benefit) and deferred income tax expense (benefit) pertaining to continuing operations.

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-Name Accounting Standards Codification
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