Asset Retirement Obligations (AROs)

9 Months Ended

Sep. 30, 2013

Asset Retirement Obligations [Line Items]

Asset Retirement Obligations (AROs)

ASSET RETIREMENT OBLIGATIONS

A reconciliation of the changes in AROs associated with long-lived assets is as follows (in millions):

	Alliant Energy						IPL						WPL
	2013			2012			2013			2012			2013			2012
Balance, January 1		$101.5			$91.1			$45.5			$56.2			$46.9			$34.9
Revisions in estimated cash flows (a)	3.4			(9.9		)	0.8			(9.2		)	2.6			(0.7		)
Liabilities settled	(0.9		)	(2.6		)	(0.1		)	(2.5		)	(0.8		)	(0.1		)
Liabilities incurred (b)	—			16.0			—			—			—			7.6
Accretion expense	2.8			2.6			1.3			1.4			1.2			1.2
Balance, September 30		$106.8			$97.2			$47.5			$45.9			$49.9			$42.9

(a) For the nine months ended September 30, 2012, IPL recorded revisions in estimated cash flows of ($8.2) million based on revised remediation timing and cost information for asbestos remediation at its Sixth Street Generating Station.

(b) For the nine months ended September 30, 2012, Resources recorded AROs of $8.4 million related to its Franklin County wind project and WPL recorded AROs of $7.6 million related to Nelson Dewey.

IPL [Member]

Asset Retirement Obligations [Line Items]

Asset Retirement Obligations (AROs)

ASSET RETIREMENT OBLIGATIONS

A reconciliation of the changes in AROs associated with long-lived assets is as follows (in millions):

	Alliant Energy						IPL						WPL
	2013			2012			2013			2012			2013			2012
Balance, January 1		$101.5			$91.1			$45.5			$56.2			$46.9			$34.9
Revisions in estimated cash flows (a)	3.4			(9.9		)	0.8			(9.2		)	2.6			(0.7		)
Liabilities settled	(0.9		)	(2.6		)	(0.1		)	(2.5		)	(0.8		)	(0.1		)
Liabilities incurred (b)	—			16.0			—			—			—			7.6
Accretion expense	2.8			2.6			1.3			1.4			1.2			1.2
Balance, September 30		$106.8			$97.2			$47.5			$45.9			$49.9			$42.9

(a) For the nine months ended September 30, 2012, IPL recorded revisions in estimated cash flows of ($8.2) million based on revised remediation timing and cost information for asbestos remediation at its Sixth Street Generating Station.

(b) For the nine months ended September 30, 2012, Resources recorded AROs of $8.4 million related to its Franklin County wind project and WPL recorded AROs of $7.6 million related to Nelson Dewey.

WPL [Member]

Asset Retirement Obligations [Line Items]

Asset Retirement Obligations (AROs)

ASSET RETIREMENT OBLIGATIONS

A reconciliation of the changes in AROs associated with long-lived assets is as follows (in millions):

	Alliant Energy						IPL						WPL
	2013			2012			2013			2012			2013			2012
Balance, January 1		$101.5			$91.1			$45.5			$56.2			$46.9			$34.9
Revisions in estimated cash flows (a)	3.4			(9.9		)	0.8			(9.2		)	2.6			(0.7		)
Liabilities settled	(0.9		)	(2.6		)	(0.1		)	(2.5		)	(0.8		)	(0.1		)
Liabilities incurred (b)	—			16.0			—			—			—			7.6
Accretion expense	2.8			2.6			1.3			1.4			1.2			1.2
Balance, September 30		$106.8			$97.2			$47.5			$45.9			$49.9			$42.9

(a) For the nine months ended September 30, 2012, IPL recorded revisions in estimated cash flows of ($8.2) million based on revised remediation timing and cost information for asbestos remediation at its Sixth Street Generating Station.

(b) For the nine months ended September 30, 2012, Resources recorded AROs of $8.4 million related to its Franklin County wind project and WPL recorded AROs of $7.6 million related to Nelson Dewey.