Commitments And Contingencies (Tables)

12 Months Ended

Dec. 31, 2015

Long-term Purchase Commitment [Line Items]

Operating Expense Purchase Obligations

At December 31, 2015, minimum future commitments related to these operating expense purchase obligations were as follows (in millions):

Alliant Energy	2016		2017		2018		2019		2020		Thereafter		Total
Purchased power (a):
DAEC (IPL) (b)		$125		$138		$131		$143		$133		$749		$1,419
Other	77		44		44		—		—		—		165
	202		182		175		143		133		749		1,584
Natural gas	173		82		52		43		32		16		398
Coal (c)	129		76		50		12		—		—		267
SO2 emission allowances	14		8		—		—		—		—		22
Other (d)	6		2		2		2		2		7		21
		$524		$350		$279		$200		$167		$772		$2,292

IPL	2016		2017		2018		2019		2020		Thereafter		Total
Purchased power (a):
DAEC (b)		$125		$138		$131		$143		$133		$749		$1,419
Other	1		—		—		—		—		—		1
	126		138		131		143		133		749		1,420
Natural gas	95		42		35		28		18		10		228
Coal (c)	70		30		17		4		—		—		121
SO2 emission allowances	14		8		—		—		—		—		22
Other (d)	1		—		—		—		—		—		1
	$306			$218		$183		$175		$151		$759		$1,792

WPL	2016		2017		2018		2019		2020		Thereafter		Total
Purchased power (a)		$76		$44		$44		$—		$—		$—		$164
Natural gas	78		40		17		15		14		6		170
Coal (c)	59		46		33		8		—		—		146
Other (d)	2		—		—		—		—		—		2
		$215		$130		$94		$23		$14		$6		$482

(a) Includes payments required by PPAs for capacity rights and minimum quantities of MWhs required to be purchased. Refer to Note 18 for additional information on purchased power transactions.

(b) Includes commitments incurred under a PPA, which grants IPL rights to purchase up to 431 MWs of capacity and the resulting energy from DAEC for a term through December 31, 2025. If energy delivered is less than the targeted energy amount, an adjustment payment will be made to IPL, which will be reflected in IPL’s fuel adjustment clause.

(c) 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, 2015 regarding expected future usage, which is subject to change.

(d) Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2015.

Schedule of Environmental Liabilities

At December 31, current environmental liabilities were included in “Other current liabilities” and non-current environmental liabilities were included in “Other liabilities” on the balance sheets as follows (in millions):

	Alliant Energy				IPL				WPL
	2015		2014		2015		2014		2015		2014
Current environmental liabilities		$2.7		$2.0		$1.7		$1.7		$1.0		$0.3
Non-current environmental liabilities	12.8		13.5		11.2		11.9		1.5		1.6
		$15.5		$15.5		$12.9		$13.6		$2.5		$1.9

At December 31, 2015, 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):

	Alliant Energy				IPL				WPL
Range of estimated future costs		$11	-	$28		$9	-	$25		$2	-	$3
Current and non-current environmental liabilities	15				13				2

IPL [Member]

Long-term Purchase Commitment [Line Items]

Operating Expense Purchase Obligations

At December 31, 2015, minimum future commitments related to these operating expense purchase obligations were as follows (in millions):

Alliant Energy	2016		2017		2018		2019		2020		Thereafter		Total
Purchased power (a):
DAEC (IPL) (b)		$125		$138		$131		$143		$133		$749		$1,419
Other	77		44		44		—		—		—		165
	202		182		175		143		133		749		1,584
Natural gas	173		82		52		43		32		16		398
Coal (c)	129		76		50		12		—		—		267
SO2 emission allowances	14		8		—		—		—		—		22
Other (d)	6		2		2		2		2		7		21
		$524		$350		$279		$200		$167		$772		$2,292

IPL	2016		2017		2018		2019		2020		Thereafter		Total
Purchased power (a):
DAEC (b)		$125		$138		$131		$143		$133		$749		$1,419
Other	1		—		—		—		—		—		1
	126		138		131		143		133		749		1,420
Natural gas	95		42		35		28		18		10		228
Coal (c)	70		30		17		4		—		—		121
SO2 emission allowances	14		8		—		—		—		—		22
Other (d)	1		—		—		—		—		—		1
	$306			$218		$183		$175		$151		$759		$1,792

WPL	2016		2017		2018		2019		2020		Thereafter		Total
Purchased power (a)		$76		$44		$44		$—		$—		$—		$164
Natural gas	78		40		17		15		14		6		170
Coal (c)	59		46		33		8		—		—		146
Other (d)	2		—		—		—		—		—		2
		$215		$130		$94		$23		$14		$6		$482

(a) Includes payments required by PPAs for capacity rights and minimum quantities of MWhs required to be purchased. Refer to Note 18 for additional information on purchased power transactions.

(b) Includes commitments incurred under a PPA, which grants IPL rights to purchase up to 431 MWs of capacity and the resulting energy from DAEC for a term through December 31, 2025. If energy delivered is less than the targeted energy amount, an adjustment payment will be made to IPL, which will be reflected in IPL’s fuel adjustment clause.

(c) 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, 2015 regarding expected future usage, which is subject to change.

(d) Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2015.

Schedule of Environmental Liabilities

At December 31, 2015, 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):

	Alliant Energy				IPL				WPL
Range of estimated future costs		$11	-	$28		$9	-	$25		$2	-	$3
Current and non-current environmental liabilities	15				13				2

At December 31, current environmental liabilities were included in “Other current liabilities” and non-current environmental liabilities were included in “Other liabilities” on the balance sheets as follows (in millions):

	Alliant Energy				IPL				WPL
	2015		2014		2015		2014		2015		2014
Current environmental liabilities		$2.7		$2.0		$1.7		$1.7		$1.0		$0.3
Non-current environmental liabilities	12.8		13.5		11.2		11.9		1.5		1.6
		$15.5		$15.5		$12.9		$13.6		$2.5		$1.9

WPL [Member]

Long-term Purchase Commitment [Line Items]

Operating Expense Purchase Obligations

At December 31, 2015, minimum future commitments related to these operating expense purchase obligations were as follows (in millions):

Alliant Energy	2016		2017		2018		2019		2020		Thereafter		Total
Purchased power (a):
DAEC (IPL) (b)		$125		$138		$131		$143		$133		$749		$1,419
Other	77		44		44		—		—		—		165
	202		182		175		143		133		749		1,584
Natural gas	173		82		52		43		32		16		398
Coal (c)	129		76		50		12		—		—		267
SO2 emission allowances	14		8		—		—		—		—		22
Other (d)	6		2		2		2		2		7		21
		$524		$350		$279		$200		$167		$772		$2,292

IPL	2016		2017		2018		2019		2020		Thereafter		Total
Purchased power (a):
DAEC (b)		$125		$138		$131		$143		$133		$749		$1,419
Other	1		—		—		—		—		—		1
	126		138		131		143		133		749		1,420
Natural gas	95		42		35		28		18		10		228
Coal (c)	70		30		17		4		—		—		121
SO2 emission allowances	14		8		—		—		—		—		22
Other (d)	1		—		—		—		—		—		1
	$306			$218		$183		$175		$151		$759		$1,792

WPL	2016		2017		2018		2019		2020		Thereafter		Total
Purchased power (a)		$76		$44		$44		$—		$—		$—		$164
Natural gas	78		40		17		15		14		6		170
Coal (c)	59		46		33		8		—		—		146
Other (d)	2		—		—		—		—		—		2
		$215		$130		$94		$23		$14		$6		$482

(a) Includes payments required by PPAs for capacity rights and minimum quantities of MWhs required to be purchased. Refer to Note 18 for additional information on purchased power transactions.

(b) Includes commitments incurred under a PPA, which grants IPL rights to purchase up to 431 MWs of capacity and the resulting energy from DAEC for a term through December 31, 2025. If energy delivered is less than the targeted energy amount, an adjustment payment will be made to IPL, which will be reflected in IPL’s fuel adjustment clause.

(c) 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, 2015 regarding expected future usage, which is subject to change.

(d) Includes individual commitments incurred during the normal course of business that exceeded $1 million at December 31, 2015.

Schedule of Environmental Liabilities

At December 31, 2015, 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):

	Alliant Energy				IPL				WPL
Range of estimated future costs		$11	-	$28		$9	-	$25		$2	-	$3
Current and non-current environmental liabilities	15				13				2

At December 31, current environmental liabilities were included in “Other current liabilities” and non-current environmental liabilities were included in “Other liabilities” on the balance sheets as follows (in millions):

	Alliant Energy				IPL				WPL
	2015		2014		2015		2014		2015		2014
Current environmental liabilities		$2.7		$2.0		$1.7		$1.7		$1.0		$0.3
Non-current environmental liabilities	12.8		13.5		11.2		11.9		1.5		1.6
		$15.5		$15.5		$12.9		$13.6		$2.5		$1.9