Debt (Tables)

6 Months Ended

Jun. 30, 2012

Debt Disclosure [Abstract]

Credit Facilities

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

	Alliant Energy	Parent
June 30, 2012	(Consolidated)	Company	IPL	WPL
Commercial paper:
Amount outstanding	$162.8	$111.8	$15.4	$35.6
Weighted average remaining maturity	4 days	5 days	2 days	2 days
Weighted average interest rates	0.4%	0.4%	0.4%	0.3%
Available credit facility capacity (a)	$787.2	$188.2	$234.6	$364.4

Other Short-Term Borrowings

	Alliant Energy						IPL						WPL
Three Months Ended June 30	2012			2011			2012			2011			2012			2011
Maximum amount outstanding (based on daily outstanding balances)		$162.8			$94.3			$30.3			$54.4			$35.6			$44.3
Average amount outstanding (based on daily outstanding balances)		$100.8			$28.7			$7.6			$18.3			$14.9			$14.2
Weighted average interest rates	0.4		%	0.3		%	0.4		%	0.3		%	0.3		%	0.3		%
Six Months Ended June 30
Maximum amount outstanding (based on daily outstanding balances)		$162.8			$96.5			$35.4			$54.4			$35.6			$96.5
Average amount outstanding (based on daily outstanding balances)		$83.6			$42.0			$10.2			$9.8			$14.0			$34.7
Weighted average interest rates	0.4		%	0.3		%	0.4		%	0.3		%	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 June 30, 2012. Refer to Note 7(b) for further discussion of $50 million of commercial paper outstanding at June 30, 2012 classified as long-term debt.