Debt (Tables)

6 Months Ended

Jun. 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
June 30, 2013	(Consolidated)	Company	IPL	WPL
Commercial paper:
Amount outstanding	$223.1	$74.2	$—	$148.9
Weighted average remaining maturity	2 days	2 days	N/A	2 days
Weighted average interest rates	0.2%	0.3%	N/A	0.2%
Available credit facility capacity (a)	$721.9	$225.8	$245.0	$251.1

	Alliant Energy						IPL						WPL
Three Months Ended June 30	2013			2012			2013			2012			2013			2012
Maximum amount outstanding (based on daily outstanding balances)		$223.1			$162.8			$6.0			$30.3			$159.4			$35.6
Average amount outstanding (based on daily outstanding balances)		$191.4			$100.8			$0.2			$7.6			$125.7			$14.9
Weighted average interest rates	0.2		%	0.4		%	0.3		%	0.4		%	0.2		%	0.3		%
Six Months Ended June 30
Maximum amount outstanding (based on daily outstanding balances)		$243.4			$162.8			$26.3			$35.4			$160.0			$35.6
Average amount outstanding (based on daily outstanding balances)		$181.2			$83.6			$2.5			$10.2			$99.4			$14.0
Weighted average interest rates	0.3		%	0.4		%	0.4		%	0.4		%	0.2		%	0.2		%

(a) Alliant Energy’s and IPL’s available credit facility capacities reflect outstanding commercial paper classified as both short- and long-term debt at June 30, 2013. Refer to Note 8(b) for further discussion of $55 million of commercial paper outstanding at June 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
June 30, 2013	(Consolidated)	Company	IPL	WPL
Commercial paper:
Amount outstanding	$223.1	$74.2	$—	$148.9
Weighted average remaining maturity	2 days	2 days	N/A	2 days
Weighted average interest rates	0.2%	0.3%	N/A	0.2%
Available credit facility capacity (a)	$721.9	$225.8	$245.0	$251.1

	Alliant Energy						IPL						WPL
Three Months Ended June 30	2013			2012			2013			2012			2013			2012
Maximum amount outstanding (based on daily outstanding balances)		$223.1			$162.8			$6.0			$30.3			$159.4			$35.6
Average amount outstanding (based on daily outstanding balances)		$191.4			$100.8			$0.2			$7.6			$125.7			$14.9
Weighted average interest rates	0.2		%	0.4		%	0.3		%	0.4		%	0.2		%	0.3		%
Six Months Ended June 30
Maximum amount outstanding (based on daily outstanding balances)		$243.4			$162.8			$26.3			$35.4			$160.0			$35.6
Average amount outstanding (based on daily outstanding balances)		$181.2			$83.6			$2.5			$10.2			$99.4			$14.0
Weighted average interest rates	0.3		%	0.4		%	0.4		%	0.4		%	0.2		%	0.2		%

(a) Alliant Energy’s and IPL’s available credit facility capacities reflect outstanding commercial paper classified as both short- and long-term debt at June 30, 2013. Refer to Note 8(b) for further discussion of $55 million of commercial paper outstanding at June 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
June 30, 2013	(Consolidated)	Company	IPL	WPL
Commercial paper:
Amount outstanding	$223.1	$74.2	$—	$148.9
Weighted average remaining maturity	2 days	2 days	N/A	2 days
Weighted average interest rates	0.2%	0.3%	N/A	0.2%
Available credit facility capacity (a)	$721.9	$225.8	$245.0	$251.1

	Alliant Energy						IPL						WPL
Three Months Ended June 30	2013			2012			2013			2012			2013			2012
Maximum amount outstanding (based on daily outstanding balances)		$223.1			$162.8			$6.0			$30.3			$159.4			$35.6
Average amount outstanding (based on daily outstanding balances)		$191.4			$100.8			$0.2			$7.6			$125.7			$14.9
Weighted average interest rates	0.2		%	0.4		%	0.3		%	0.4		%	0.2		%	0.3		%
Six Months Ended June 30
Maximum amount outstanding (based on daily outstanding balances)		$243.4			$162.8			$26.3			$35.4			$160.0			$35.6
Average amount outstanding (based on daily outstanding balances)		$181.2			$83.6			$2.5			$10.2			$99.4			$14.0
Weighted average interest rates	0.3		%	0.4		%	0.4		%	0.4		%	0.2		%	0.2		%

(a) Alliant Energy’s and IPL’s available credit facility capacities reflect outstanding commercial paper classified as both short- and long-term debt at June 30, 2013. Refer to Note 8(b) for further discussion of $55 million of commercial paper outstanding at June 30, 2013 classified as long-term debt on Alliant Energy’s and IPL’s Condensed Consolidated Balance Sheets.