Debt

3 Months Ended

Mar. 31, 2016

Debt [Line Items]

Debt

DEBT

Short-term Debt - Information regarding commercial paper classified as short-term debt and back-stopped by the credit facilities was as follows (dollars in millions):

	Alliant Energy	Parent
March 31, 2016	(Consolidated)	Company	IPL	WPL
Commercial paper:
Amount outstanding	$213.4	$187.9	$—	$25.5
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	$786.6	$112.1	$300.0	$374.5

	Alliant Energy						IPL					WPL
Three Months Ended March 31	2016			2015			2016		2015			2016	2015
Maximum amount outstanding (based on daily outstanding balances)		$242.6			$151.3			$—		$1.4		$55.7		$—
Average amount outstanding (based on daily outstanding balances)		$199.0			$127.9			$—		$—		$25.8		$—
Weighted average interest rates	0.6		%	0.4		%	N/A		0.4		%	0.4%	N/A

IPL [Member]

Debt [Line Items]

Debt

DEBT

Short-term Debt - Information regarding commercial paper classified as short-term debt and back-stopped by the credit facilities was as follows (dollars in millions):

	Alliant Energy	Parent
March 31, 2016	(Consolidated)	Company	IPL	WPL
Commercial paper:
Amount outstanding	$213.4	$187.9	$—	$25.5
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	$786.6	$112.1	$300.0	$374.5

	Alliant Energy						IPL					WPL
Three Months Ended March 31	2016			2015			2016		2015			2016	2015
Maximum amount outstanding (based on daily outstanding balances)		$242.6			$151.3			$—		$1.4		$55.7		$—
Average amount outstanding (based on daily outstanding balances)		$199.0			$127.9			$—		$—		$25.8		$—
Weighted average interest rates	0.6		%	0.4		%	N/A		0.4		%	0.4%	N/A

WPL [Member]

Debt [Line Items]

Debt

DEBT

Short-term Debt - Information regarding commercial paper classified as short-term debt and back-stopped by the credit facilities was as follows (dollars in millions):

	Alliant Energy	Parent
March 31, 2016	(Consolidated)	Company	IPL	WPL
Commercial paper:
Amount outstanding	$213.4	$187.9	$—	$25.5
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	$786.6	$112.1	$300.0	$374.5

	Alliant Energy						IPL					WPL
Three Months Ended March 31	2016			2015			2016		2015			2016	2015
Maximum amount outstanding (based on daily outstanding balances)		$242.6			$151.3			$—		$1.4		$55.7		$—
Average amount outstanding (based on daily outstanding balances)		$199.0			$127.9			$—		$—		$25.8		$—
Weighted average interest rates	0.6		%	0.4		%	N/A		0.4		%	0.4%	N/A