Commitments And Contingencies (Tables)

12 Months Ended

Dec. 31, 2016

Long-term Purchase Commitment [Line Items]

Operating Expense Purchase Obligations

At December 31, 2016, minimum future commitments related to these operating expense purchase obligations were as follows (in millions):

Alliant Energy	2017		2018		2019		2020		2021		Thereafter		Total
Purchased power (a)		$185		$189		$159		$137		$149		$599		$1,418
Natural gas	223		142		115		98		69		124		771
Coal (b)	105		54		18		—		—		—		177
Other (c)	16		4		5		2		2		5		34
		$529		$389		$297		$237		$220		$728		$2,400

IPL	2017		2018		2019		2020		2021		Thereafter		Total
Purchased power (a)		$138		$131		$144		$137		$149		$599		$1,298
Natural gas	120		74		55		39		23		71		382
Coal (b)	49		19		9		—		—		—		77
Other (c)	15		1		1		—		—		—		17
		$322		$225		$209		$176		$172		$670		$1,774

WPL	2017		2018		2019		2020		2021		Thereafter		Total
Purchased power (a)		$47		$58		$15		$—		$—		$—		$120
Natural gas	103		68		60		59		46		53		389
Coal (b)	56		35		9		—		—		—		100
Other (c)	—		1		1		—		—		—		2
		$206		$162		$85		$59		$46		$53		$611

(a) Includes payments required by PPAs for capacity rights and minimum quantities of MWhs required to be purchased.

(b) Corporate Services entered into system-wide coal contracts on behalf of IPL and WPL that include minimum future commitments. These commitments were assigned to IPL and WPL based on information available as of December 31, 2016 regarding expected future usage, which is subject to change.

(c) Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2016.

Schedule of Environmental Liabilities

At December 31, 2016, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, were as follows (in millions). At December 31, 2016, such amounts for WPL were not material.

	Alliant Energy				IPL
Range of estimated future costs		$14	-	$27		$12	-	$24
Current and non-current environmental liabilities	16				13

IPL [Member]

Long-term Purchase Commitment [Line Items]

Operating Expense Purchase Obligations

At December 31, 2016, minimum future commitments related to these operating expense purchase obligations were as follows (in millions):

Alliant Energy	2017		2018		2019		2020		2021		Thereafter		Total
Purchased power (a)		$185		$189		$159		$137		$149		$599		$1,418
Natural gas	223		142		115		98		69		124		771
Coal (b)	105		54		18		—		—		—		177
Other (c)	16		4		5		2		2		5		34
		$529		$389		$297		$237		$220		$728		$2,400

IPL	2017		2018		2019		2020		2021		Thereafter		Total
Purchased power (a)		$138		$131		$144		$137		$149		$599		$1,298
Natural gas	120		74		55		39		23		71		382
Coal (b)	49		19		9		—		—		—		77
Other (c)	15		1		1		—		—		—		17
		$322		$225		$209		$176		$172		$670		$1,774

WPL	2017		2018		2019		2020		2021		Thereafter		Total
Purchased power (a)		$47		$58		$15		$—		$—		$—		$120
Natural gas	103		68		60		59		46		53		389
Coal (b)	56		35		9		—		—		—		100
Other (c)	—		1		1		—		—		—		2
		$206		$162		$85		$59		$46		$53		$611

(a) Includes payments required by PPAs for capacity rights and minimum quantities of MWhs required to be purchased.

(b) Corporate Services entered into system-wide coal contracts on behalf of IPL and WPL that include minimum future commitments. These commitments were assigned to IPL and WPL based on information available as of December 31, 2016 regarding expected future usage, which is subject to change.

(c) Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2016.

Schedule of Environmental Liabilities

At December 31, 2016, estimated future costs expected to be incurred for the investigation, remediation and monitoring of the MGP sites, as well as environmental liabilities recorded on the balance sheets for these sites, were as follows (in millions). At December 31, 2016, such amounts for WPL were not material.

	Alliant Energy				IPL
Range of estimated future costs		$14	-	$27		$12	-	$24
Current and non-current environmental liabilities	16				13

WPL [Member]

Long-term Purchase Commitment [Line Items]

Operating Expense Purchase Obligations

At December 31, 2016, minimum future commitments related to these operating expense purchase obligations were as follows (in millions):

Alliant Energy	2017		2018		2019		2020		2021		Thereafter		Total
Purchased power (a)		$185		$189		$159		$137		$149		$599		$1,418
Natural gas	223		142		115		98		69		124		771
Coal (b)	105		54		18		—		—		—		177
Other (c)	16		4		5		2		2		5		34
		$529		$389		$297		$237		$220		$728		$2,400

IPL	2017		2018		2019		2020		2021		Thereafter		Total
Purchased power (a)		$138		$131		$144		$137		$149		$599		$1,298
Natural gas	120		74		55		39		23		71		382
Coal (b)	49		19		9		—		—		—		77
Other (c)	15		1		1		—		—		—		17
		$322		$225		$209		$176		$172		$670		$1,774

WPL	2017		2018		2019		2020		2021		Thereafter		Total
Purchased power (a)		$47		$58		$15		$—		$—		$—		$120
Natural gas	103		68		60		59		46		53		389
Coal (b)	56		35		9		—		—		—		100
Other (c)	—		1		1		—		—		—		2
		$206		$162		$85		$59		$46		$53		$611

(a) Includes payments required by PPAs for capacity rights and minimum quantities of MWhs required to be purchased.

(b) Corporate Services entered into system-wide coal contracts on behalf of IPL and WPL that include minimum future commitments. These commitments were assigned to IPL and WPL based on information available as of December 31, 2016 regarding expected future usage, which is subject to change.

(c) Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2016.