Derivative Instruments (Tables)

12 Months Ended

Dec. 31, 2019

Derivative [Line Items]

Notional Amounts of Derivative Instruments

As of December 31, 2019, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):

	FTRs		Natural Gas		Coal		Diesel Fuel
	MWhs	Years	Dths	Years	Tons	Years	Gallons	Years
Alliant Energy	11,671	2020	189,287	2020-2026	6,194	2020-2021	5,040	2020-2021
IPL	5,497	2020	102,758	2020-2026	2,700	2020-2021	—
WPL	6,174	2020	86,529	2020-2026	3,494	2020-2021	5,040	2020-2021

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
	2019		2018		2019		2018		2019		2018
Current derivative assets		$15.8		$24.6		$12.1		$16.1		$3.7		$8.5
Non-current derivative assets	11.0		3.7		10.2		1.6		0.8		2.1
Current derivative liabilities	19.0		5.6		8.9		3.1		10.1		2.5
Non-current derivative liabilities	18.6		17.7		8.5		8.1		10.1		9.6

IPL [Member]

Derivative [Line Items]

Notional Amounts of Derivative Instruments

As of December 31, 2019, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):

	FTRs		Natural Gas		Coal		Diesel Fuel
	MWhs	Years	Dths	Years	Tons	Years	Gallons	Years
Alliant Energy	11,671	2020	189,287	2020-2026	6,194	2020-2021	5,040	2020-2021
IPL	5,497	2020	102,758	2020-2026	2,700	2020-2021	—
WPL	6,174	2020	86,529	2020-2026	3,494	2020-2021	5,040	2020-2021

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
	2019		2018		2019		2018		2019		2018
Current derivative assets		$15.8		$24.6		$12.1		$16.1		$3.7		$8.5
Non-current derivative assets	11.0		3.7		10.2		1.6		0.8		2.1
Current derivative liabilities	19.0		5.6		8.9		3.1		10.1		2.5
Non-current derivative liabilities	18.6		17.7		8.5		8.1		10.1		9.6

WPL [Member]

Derivative [Line Items]

Notional Amounts of Derivative Instruments

As of December 31, 2019, gross notional amounts and settlement/delivery years related to outstanding swap contracts, option contracts, physical forward contracts and FTRs that were accounted for as commodity derivative instruments were as follows (units in thousands):

	FTRs		Natural Gas		Coal		Diesel Fuel
	MWhs	Years	Dths	Years	Tons	Years	Gallons	Years
Alliant Energy	11,671	2020	189,287	2020-2026	6,194	2020-2021	5,040	2020-2021
IPL	5,497	2020	102,758	2020-2026	2,700	2020-2021	—
WPL	6,174	2020	86,529	2020-2026	3,494	2020-2021	5,040	2020-2021

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
	2019		2018		2019		2018		2019		2018
Current derivative assets		$15.8		$24.6		$12.1		$16.1		$3.7		$8.5
Non-current derivative assets	11.0		3.7		10.2		1.6		0.8		2.1
Current derivative liabilities	19.0		5.6		8.9		3.1		10.1		2.5
Non-current derivative liabilities	18.6		17.7		8.5		8.1		10.1		9.6