Debt (Tables)

9 Months Ended

Sep. 30, 2013

Debt Disclosure [Line Items]

Other Short-Term Borrowings

Information regarding commercial paper classified as short-term debt and back-stopped by Alliant Energy’s, IPL’s and WPL’s credit facilities was as follows (dollars in millions):

	Alliant Energy	Parent
September 30, 2013	(Consolidated)	Company	IPL	WPL
Commercial paper:
Amount outstanding	$237.3	$93.9	$—	$143.4
Weighted average remaining maturity	1 day	2 days	N/A	1 day
Weighted average interest rates	0.2%	0.2%	N/A	0.1%
Available credit facility capacity (a)	$697.7	$206.1	$235.0	$256.6

	Alliant Energy						IPL						WPL
Three Months Ended September 30	2013			2012			2013			2012			2013			2012
Maximum amount outstanding (based on daily outstanding balances)		$284.1			$185.3			$—			$19.5			$165.4			$35.6
Average amount outstanding (based on daily outstanding balances)		$228.8			$133.0			$—			$1.3			$140.9			$11.9
Weighted average interest rates	0.2		%	0.4		%	N/A			0.4		%	0.2		%	0.3		%
Nine Months Ended September 30
Maximum amount outstanding (based on daily outstanding balances)		$284.1			$185.3			$26.3			$35.4			$165.4			$35.6
Average amount outstanding (based on daily outstanding balances)		$197.2			$100.2			$1.7			$7.2			$113.4			$13.3
Weighted average interest rates	0.2		%	0.4		%	0.4		%	0.4		%	0.2		%	0.3		%

(a) Alliant Energy’s and IPL’s available credit facility capacities reflect outstanding commercial paper classified as both short- and long-term debt at September 30, 2013. Refer to Note 8(b) for further discussion of $65 million of commercial paper outstanding at September 30, 2013 classified as long-term debt on Alliant Energy’s and IPL’s Condensed Consolidated Balance Sheets.

IPL [Member]

Debt Disclosure [Line Items]

Other Short-Term Borrowings

Information regarding commercial paper classified as short-term debt and back-stopped by Alliant Energy’s, IPL’s and WPL’s credit facilities was as follows (dollars in millions):

	Alliant Energy	Parent
September 30, 2013	(Consolidated)	Company	IPL	WPL
Commercial paper:
Amount outstanding	$237.3	$93.9	$—	$143.4
Weighted average remaining maturity	1 day	2 days	N/A	1 day
Weighted average interest rates	0.2%	0.2%	N/A	0.1%
Available credit facility capacity (a)	$697.7	$206.1	$235.0	$256.6

	Alliant Energy						IPL						WPL
Three Months Ended September 30	2013			2012			2013			2012			2013			2012
Maximum amount outstanding (based on daily outstanding balances)		$284.1			$185.3			$—			$19.5			$165.4			$35.6
Average amount outstanding (based on daily outstanding balances)		$228.8			$133.0			$—			$1.3			$140.9			$11.9
Weighted average interest rates	0.2		%	0.4		%	N/A			0.4		%	0.2		%	0.3		%
Nine Months Ended September 30
Maximum amount outstanding (based on daily outstanding balances)		$284.1			$185.3			$26.3			$35.4			$165.4			$35.6
Average amount outstanding (based on daily outstanding balances)		$197.2			$100.2			$1.7			$7.2			$113.4			$13.3
Weighted average interest rates	0.2		%	0.4		%	0.4		%	0.4		%	0.2		%	0.3		%

(a) Alliant Energy’s and IPL’s available credit facility capacities reflect outstanding commercial paper classified as both short- and long-term debt at September 30, 2013. Refer to Note 8(b) for further discussion of $65 million of commercial paper outstanding at September 30, 2013 classified as long-term debt on Alliant Energy’s and IPL’s Condensed Consolidated Balance Sheets.

WPL [Member]

Debt Disclosure [Line Items]

Other Short-Term Borrowings

Information regarding commercial paper classified as short-term debt and back-stopped by Alliant Energy’s, IPL’s and WPL’s credit facilities was as follows (dollars in millions):

	Alliant Energy	Parent
September 30, 2013	(Consolidated)	Company	IPL	WPL
Commercial paper:
Amount outstanding	$237.3	$93.9	$—	$143.4
Weighted average remaining maturity	1 day	2 days	N/A	1 day
Weighted average interest rates	0.2%	0.2%	N/A	0.1%
Available credit facility capacity (a)	$697.7	$206.1	$235.0	$256.6

	Alliant Energy						IPL						WPL
Three Months Ended September 30	2013			2012			2013			2012			2013			2012
Maximum amount outstanding (based on daily outstanding balances)		$284.1			$185.3			$—			$19.5			$165.4			$35.6
Average amount outstanding (based on daily outstanding balances)		$228.8			$133.0			$—			$1.3			$140.9			$11.9
Weighted average interest rates	0.2		%	0.4		%	N/A			0.4		%	0.2		%	0.3		%
Nine Months Ended September 30
Maximum amount outstanding (based on daily outstanding balances)		$284.1			$185.3			$26.3			$35.4			$165.4			$35.6
Average amount outstanding (based on daily outstanding balances)		$197.2			$100.2			$1.7			$7.2			$113.4			$13.3
Weighted average interest rates	0.2		%	0.4		%	0.4		%	0.4		%	0.2		%	0.3		%

(a) Alliant Energy’s and IPL’s available credit facility capacities reflect outstanding commercial paper classified as both short- and long-term debt at September 30, 2013. Refer to Note 8(b) for further discussion of $65 million of commercial paper outstanding at September 30, 2013 classified as long-term debt on Alliant Energy’s and IPL’s Condensed Consolidated Balance Sheets.