Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2015

Derivative [Line Items]

Notional Amounts of Derivative Instruments

As of December 31, 2015, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts, FTRs and coal contracts that were accounted for as commodity derivative instruments were as follows (units in thousands):

	Electricity		FTRs		Natural Gas		Coal
	MWhs	Years	MWhs	Years	Dths	Years	Tons	Years
Alliant Energy	5,868	2016-2018	9,880	2016	104,096	2016-2020	4,945	2016-2018
IPL	809	2016	5,622	2016	55,985	2016-2020	1,966	2016-2018
WPL	5,059	2016-2018	4,258	2016	48,111	2016-2020	2,979	2016-2018

Fair Value of Financial Instruments

At December 31, 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	2015		2014		2015		2014		2015		2014
Current derivative assets		$15.1		$30.5		$13.8		$27.4		$1.3		$3.1
Non-current derivative assets	3.3		8.1		1.7		0.6		1.6		7.5
Current derivative liabilities	47.3		28.1		18.5		16.4		28.8		11.7
Non-current derivative liabilities	17.3		9.5		4.9		3.1		12.4		6.4

IPL [Member]

Derivative [Line Items]

Notional Amounts of Derivative Instruments

As of December 31, 2015, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts, FTRs and coal contracts that were accounted for as commodity derivative instruments were as follows (units in thousands):

	Electricity		FTRs		Natural Gas		Coal
	MWhs	Years	MWhs	Years	Dths	Years	Tons	Years
Alliant Energy	5,868	2016-2018	9,880	2016	104,096	2016-2020	4,945	2016-2018
IPL	809	2016	5,622	2016	55,985	2016-2020	1,966	2016-2018
WPL	5,059	2016-2018	4,258	2016	48,111	2016-2020	2,979	2016-2018

Fair Value of Financial Instruments

At December 31, 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	2015		2014		2015		2014		2015		2014
Current derivative assets		$15.1		$30.5		$13.8		$27.4		$1.3		$3.1
Non-current derivative assets	3.3		8.1		1.7		0.6		1.6		7.5
Current derivative liabilities	47.3		28.1		18.5		16.4		28.8		11.7
Non-current derivative liabilities	17.3		9.5		4.9		3.1		12.4		6.4

WPL [Member]

Derivative [Line Items]

Notional Amounts of Derivative Instruments

As of December 31, 2015, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts, FTRs and coal contracts that were accounted for as commodity derivative instruments were as follows (units in thousands):

	Electricity		FTRs		Natural Gas		Coal
	MWhs	Years	MWhs	Years	Dths	Years	Tons	Years
Alliant Energy	5,868	2016-2018	9,880	2016	104,096	2016-2020	4,945	2016-2018
IPL	809	2016	5,622	2016	55,985	2016-2020	1,966	2016-2018
WPL	5,059	2016-2018	4,258	2016	48,111	2016-2020	2,979	2016-2018

Fair Value of Financial Instruments

At December 31, 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	2015		2014		2015		2014		2015		2014
Current derivative assets		$15.1		$30.5		$13.8		$27.4		$1.3		$3.1
Non-current derivative assets	3.3		8.1		1.7		0.6		1.6		7.5
Current derivative liabilities	47.3		28.1		18.5		16.4		28.8		11.7
Non-current derivative liabilities	17.3		9.5		4.9		3.1		12.4		6.4