Derivative Instruments (Tables)

3 Months Ended

Mar. 31, 2017

Derivative Instruments [Line Items]

Notional Amounts Of Derivative Instruments

As of March 31, 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	2,304	2017-2018	3,537	2017	160,048	2017-2026	4,113	2017-2019	5,796	2017-2018
IPL	—	—	2,229	2017	72,924	2017-2026	1,680	2017-2019	—	—
WPL	2,304	2017-2018	1,308	2017	87,124	2017-2026	2,433	2017-2018	5,796	2017-2018

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
Commodity contracts	March 31, 2017		December 31, 2016		March 31, 2017		December 31, 2016		March 31, 2017		December 31, 2016
Current derivative assets		$12.2		$29.4		$8.2		$19.1		$4.0		$10.3
Non-current derivative assets	1.1		12.0		0.6		1.7		0.5		10.3
Current derivative liabilities	13.4		13.3		2.9		2.7		10.5		10.6
Non-current derivative liabilities	31.9		15.3		13.4		5.6		18.5		9.7

IPL [Member]

Derivative Instruments [Line Items]

Notional Amounts Of Derivative Instruments

As of March 31, 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	2,304	2017-2018	3,537	2017	160,048	2017-2026	4,113	2017-2019	5,796	2017-2018
IPL	—	—	2,229	2017	72,924	2017-2026	1,680	2017-2019	—	—
WPL	2,304	2017-2018	1,308	2017	87,124	2017-2026	2,433	2017-2018	5,796	2017-2018

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
Commodity contracts	March 31, 2017		December 31, 2016		March 31, 2017		December 31, 2016		March 31, 2017		December 31, 2016
Current derivative assets		$12.2		$29.4		$8.2		$19.1		$4.0		$10.3
Non-current derivative assets	1.1		12.0		0.6		1.7		0.5		10.3
Current derivative liabilities	13.4		13.3		2.9		2.7		10.5		10.6
Non-current derivative liabilities	31.9		15.3		13.4		5.6		18.5		9.7

WPL [Member]

Derivative Instruments [Line Items]

Notional Amounts Of Derivative Instruments

As of March 31, 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	2,304	2017-2018	3,537	2017	160,048	2017-2026	4,113	2017-2019	5,796	2017-2018
IPL	—	—	2,229	2017	72,924	2017-2026	1,680	2017-2019	—	—
WPL	2,304	2017-2018	1,308	2017	87,124	2017-2026	2,433	2017-2018	5,796	2017-2018

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
Commodity contracts	March 31, 2017		December 31, 2016		March 31, 2017		December 31, 2016		March 31, 2017		December 31, 2016
Current derivative assets		$12.2		$29.4		$8.2		$19.1		$4.0		$10.3
Non-current derivative assets	1.1		12.0		0.6		1.7		0.5		10.3
Current derivative liabilities	13.4		13.3		2.9		2.7		10.5		10.6
Non-current derivative liabilities	31.9		15.3		13.4		5.6		18.5		9.7