Derivative Instruments (Tables)

9 Months Ended

Sep. 30, 2017

Derivative Instruments [Line Items]

Notional Amounts Of Derivative Instruments

As of September 30, 2017, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts, FTRs, coal contracts and diesel fuel contracts that were accounted for as commodity derivative instruments were as follows (units in thousands):

	Electricity		FTRs		Natural Gas		Coal		Diesel Fuel
	MWhs	Years	MWhs	Years	Dths	Years	Tons	Years	Gallons	Years
Alliant Energy	1,645	2017-2018	14,745	2017-2018	173,234	2017-2026	4,963	2017-2019	7,308	2017-2019
IPL	—	—	9,219	2017-2018	79,561	2017-2026	1,820	2017-2019	—	—
WPL	1,645	2017-2018	5,526	2017-2018	93,673	2017-2026	3,143	2017-2018	7,308	2017-2019

Fair Value Of Financial Instruments

The fair values of current derivative assets are included in “Other current assets,” non-current derivative assets are included in “Deferred charges and other,” current derivative liabilities are included in “Other current liabilities” and non-current derivative liabilities are included in “Other liabilities” on the balance sheets as follows (in millions):

	Alliant Energy				IPL				WPL
	September 30, 2017		December 31, 2016		September 30, 2017		December 31, 2016		September 30, 2017		December 31, 2016
Current derivative assets		$26.7		$29.4		$20.3		$19.1		$6.4		$10.3
Non-current derivative assets	2.7		12.0		0.8		1.7		1.9		10.3
Current derivative liabilities	18.5		13.3		4.6		2.7		13.9		10.6
Non-current derivative liabilities	26.6		15.3		14.1		5.6		12.5		9.7

IPL [Member]

Derivative Instruments [Line Items]

Notional Amounts Of Derivative Instruments

As of September 30, 2017, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts, FTRs, coal contracts and diesel fuel contracts that were accounted for as commodity derivative instruments were as follows (units in thousands):

	Electricity		FTRs		Natural Gas		Coal		Diesel Fuel
	MWhs	Years	MWhs	Years	Dths	Years	Tons	Years	Gallons	Years
Alliant Energy	1,645	2017-2018	14,745	2017-2018	173,234	2017-2026	4,963	2017-2019	7,308	2017-2019
IPL	—	—	9,219	2017-2018	79,561	2017-2026	1,820	2017-2019	—	—
WPL	1,645	2017-2018	5,526	2017-2018	93,673	2017-2026	3,143	2017-2018	7,308	2017-2019

Fair Value Of Financial Instruments

The fair values of current derivative assets are included in “Other current assets,” non-current derivative assets are included in “Deferred charges and other,” current derivative liabilities are included in “Other current liabilities” and non-current derivative liabilities are included in “Other liabilities” on the balance sheets as follows (in millions):

	Alliant Energy				IPL				WPL
	September 30, 2017		December 31, 2016		September 30, 2017		December 31, 2016		September 30, 2017		December 31, 2016
Current derivative assets		$26.7		$29.4		$20.3		$19.1		$6.4		$10.3
Non-current derivative assets	2.7		12.0		0.8		1.7		1.9		10.3
Current derivative liabilities	18.5		13.3		4.6		2.7		13.9		10.6
Non-current derivative liabilities	26.6		15.3		14.1		5.6		12.5		9.7

WPL [Member]

Derivative Instruments [Line Items]

Notional Amounts Of Derivative Instruments

As of September 30, 2017, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts, FTRs, coal contracts and diesel fuel contracts that were accounted for as commodity derivative instruments were as follows (units in thousands):

	Electricity		FTRs		Natural Gas		Coal		Diesel Fuel
	MWhs	Years	MWhs	Years	Dths	Years	Tons	Years	Gallons	Years
Alliant Energy	1,645	2017-2018	14,745	2017-2018	173,234	2017-2026	4,963	2017-2019	7,308	2017-2019
IPL	—	—	9,219	2017-2018	79,561	2017-2026	1,820	2017-2019	—	—
WPL	1,645	2017-2018	5,526	2017-2018	93,673	2017-2026	3,143	2017-2018	7,308	2017-2019

Fair Value Of Financial Instruments

The fair values of current derivative assets are included in “Other current assets,” non-current derivative assets are included in “Deferred charges and other,” current derivative liabilities are included in “Other current liabilities” and non-current derivative liabilities are included in “Other liabilities” on the balance sheets as follows (in millions):

	Alliant Energy				IPL				WPL
	September 30, 2017		December 31, 2016		September 30, 2017		December 31, 2016		September 30, 2017		December 31, 2016
Current derivative assets		$26.7		$29.4		$20.3		$19.1		$6.4		$10.3
Non-current derivative assets	2.7		12.0		0.8		1.7		1.9		10.3
Current derivative liabilities	18.5		13.3		4.6		2.7		13.9		10.6
Non-current derivative liabilities	26.6		15.3		14.1		5.6		12.5		9.7