Debt (Tables)

6 Months Ended

Jun. 30, 2016

Debt Disclosure [Line Items]

Other Short-Term Borrowings

Information regarding commercial paper classified as short-term debt was as follows (dollars in millions):

	Alliant Energy	Parent
June 30, 2016	(Consolidated)	Company	IPL	WPL
Commercial paper:
Amount outstanding	$220.6	$174.8	$—	$45.8
Weighted average remaining maturity	2 days	2 days	N/A	1 day
Weighted average interest rates	0.6%	0.6%	N/A	0.4%
Available credit facility capacity (a)	$712.4	$125.2	$233.0	$354.2

	Alliant Energy						IPL						WPL
Three Months Ended June 30	2016			2015			2016			2015			2016	2015
Maximum amount outstanding (based on daily outstanding balances)		$229.9			$152.6			$1.7			$9.7		$62.9		$—
Average amount outstanding (based on daily outstanding balances)		$213.0			$93.2			$—			$0.1		$37.4		$—
Weighted average interest rates	0.6		%	0.5		%	0.6		%	0.5		%	0.4%	N/A
Six Months Ended June 30
Maximum amount outstanding (based on daily outstanding balances)		$242.6			$152.6			$1.7			$9.7		$62.9		$—
Average amount outstanding (based on daily outstanding balances)		$206.0			$110.5			$—			$0.1		$31.6		$—
Weighted average interest rates	0.6		%	0.4		%	0.6		%	0.5		%	0.4%	N/A

(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, 2016.

IPL [Member]

Debt Disclosure [Line Items]

Other Short-Term Borrowings

Information regarding commercial paper classified as short-term debt was as follows (dollars in millions):

	Alliant Energy	Parent
June 30, 2016	(Consolidated)	Company	IPL	WPL
Commercial paper:
Amount outstanding	$220.6	$174.8	$—	$45.8
Weighted average remaining maturity	2 days	2 days	N/A	1 day
Weighted average interest rates	0.6%	0.6%	N/A	0.4%
Available credit facility capacity (a)	$712.4	$125.2	$233.0	$354.2

	Alliant Energy						IPL						WPL
Three Months Ended June 30	2016			2015			2016			2015			2016	2015
Maximum amount outstanding (based on daily outstanding balances)		$229.9			$152.6			$1.7			$9.7		$62.9		$—
Average amount outstanding (based on daily outstanding balances)		$213.0			$93.2			$—			$0.1		$37.4		$—
Weighted average interest rates	0.6		%	0.5		%	0.6		%	0.5		%	0.4%	N/A
Six Months Ended June 30
Maximum amount outstanding (based on daily outstanding balances)		$242.6			$152.6			$1.7			$9.7		$62.9		$—
Average amount outstanding (based on daily outstanding balances)		$206.0			$110.5			$—			$0.1		$31.6		$—
Weighted average interest rates	0.6		%	0.4		%	0.6		%	0.5		%	0.4%	N/A

(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, 2016.

WPL [Member]

Debt Disclosure [Line Items]

Other Short-Term Borrowings

Information regarding commercial paper classified as short-term debt was as follows (dollars in millions):

	Alliant Energy	Parent
June 30, 2016	(Consolidated)	Company	IPL	WPL
Commercial paper:
Amount outstanding	$220.6	$174.8	$—	$45.8
Weighted average remaining maturity	2 days	2 days	N/A	1 day
Weighted average interest rates	0.6%	0.6%	N/A	0.4%
Available credit facility capacity (a)	$712.4	$125.2	$233.0	$354.2

	Alliant Energy						IPL						WPL
Three Months Ended June 30	2016			2015			2016			2015			2016	2015
Maximum amount outstanding (based on daily outstanding balances)		$229.9			$152.6			$1.7			$9.7		$62.9		$—
Average amount outstanding (based on daily outstanding balances)		$213.0			$93.2			$—			$0.1		$37.4		$—
Weighted average interest rates	0.6		%	0.5		%	0.6		%	0.5		%	0.4%	N/A
Six Months Ended June 30
Maximum amount outstanding (based on daily outstanding balances)		$242.6			$152.6			$1.7			$9.7		$62.9		$—
Average amount outstanding (based on daily outstanding balances)		$206.0			$110.5			$—			$0.1		$31.6		$—
Weighted average interest rates	0.6		%	0.4		%	0.6		%	0.5		%	0.4%	N/A

(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, 2016.