Summary Of Significant Accounting Policies (Tables)

12 Months Ended

Dec. 31, 2018

Schedule of Average Rates of Depreciation

The average rates of depreciation for electric, gas and other properties, consistent with current rate-making practices, were as follows:

	IPL			WPL
	2018	2017	2016	2018	2017	2016
Electric - generation	3.6%	3.5%	3.5%	3.6%	3.5%	3.1%
Electric - distribution	2.8%	2.4%	2.4%	2.6%	2.6%	2.6%
Electric - other	4.7%	4.5%	4.2%	5.7%	6.9%	4.7%
Gas	3.2%	3.4%	3.3%	2.5%	2.5%	2.5%
Other	5.2%	4.0%	3.9%	5.8%	6.0%	5.9%

Schedule of Allowance for Funds Used During Construction Rate

The AFUDC rates, computed in accordance with the prescribed regulatory formula, were as follows:

	2018	2017	2016
IPL (Marshalltown CWIP)	N/A	7.8%	7.9%
IPL (Wind generation CWIP)	7.5%	7.6%	N/A
IPL (other CWIP)	7.5%	7.6%	7.7%
WPL (retail jurisdiction)	7.7%	7.6%	8.2%
WPL (wholesale jurisdiction)	7.2%	6.0%	6.7%

IPL [Member]

Schedule of Average Rates of Depreciation

The average rates of depreciation for electric, gas and other properties, consistent with current rate-making practices, were as follows:

	IPL			WPL
	2018	2017	2016	2018	2017	2016
Electric - generation	3.6%	3.5%	3.5%	3.6%	3.5%	3.1%
Electric - distribution	2.8%	2.4%	2.4%	2.6%	2.6%	2.6%
Electric - other	4.7%	4.5%	4.2%	5.7%	6.9%	4.7%
Gas	3.2%	3.4%	3.3%	2.5%	2.5%	2.5%
Other	5.2%	4.0%	3.9%	5.8%	6.0%	5.9%

Schedule of Allowance for Funds Used During Construction Rate

The AFUDC rates, computed in accordance with the prescribed regulatory formula, were as follows:

	2018	2017	2016
IPL (Marshalltown CWIP)	N/A	7.8%	7.9%
IPL (Wind generation CWIP)	7.5%	7.6%	N/A
IPL (other CWIP)	7.5%	7.6%	7.7%
WPL (retail jurisdiction)	7.7%	7.6%	8.2%
WPL (wholesale jurisdiction)	7.2%	6.0%	6.7%

WPL [Member]

Schedule of Average Rates of Depreciation

The average rates of depreciation for electric, gas and other properties, consistent with current rate-making practices, were as follows:

	IPL			WPL
	2018	2017	2016	2018	2017	2016
Electric - generation	3.6%	3.5%	3.5%	3.6%	3.5%	3.1%
Electric - distribution	2.8%	2.4%	2.4%	2.6%	2.6%	2.6%
Electric - other	4.7%	4.5%	4.2%	5.7%	6.9%	4.7%
Gas	3.2%	3.4%	3.3%	2.5%	2.5%	2.5%
Other	5.2%	4.0%	3.9%	5.8%	6.0%	5.9%

Schedule of Allowance for Funds Used During Construction Rate

The AFUDC rates, computed in accordance with the prescribed regulatory formula, were as follows:

	2018	2017	2016
IPL (Marshalltown CWIP)	N/A	7.8%	7.9%
IPL (Wind generation CWIP)	7.5%	7.6%	N/A
IPL (other CWIP)	7.5%	7.6%	7.7%
WPL (retail jurisdiction)	7.7%	7.6%	8.2%
WPL (wholesale jurisdiction)	7.2%	6.0%	6.7%