Related Parties (Tables)

9 Months Ended

Sep. 30, 2013

Related Party Transaction [Line Items]

Sales Credited And Purchases Billed

The sales credited to and purchases billed to IPL and WPL for the three and nine months ended September 30 were as follows (in millions):

	IPL								WPL
	Three Months				Nine Months				Three Months				Nine Months
	2013		2012		2013		2012		2013		2012		2013		2012
Sales credited		$2		$3		$5		$7		$3		$4		$10		$10
Purchases billed	108		87		260		237		16		13		44		50

Corporate Services Billings

The amounts billed to IPL and WPL for the three and nine months ended September 30 were as follows (in millions):

	IPL								WPL
	Three Months				Nine Months				Three Months				Nine Months
	2013		2012		2013		2012		2013		2012		2013		2012
Corporate Services billings		$39		$34		$107		$97		$28		$26		$77		$76

Net Intercompany Payables

Net intercompany payables to Corporate Services were as follows (in millions):

	IPL		WPL
	September 30, 2013	December 31, 2012	September 30, 2013	December 31, 2012
Net payables to Corporate Services	$95	$72	$46	$40

Related Amounts Billed Between Parties

The related amounts billed between the parties for the three and nine months ended September 30 were as follows (in millions):

	Three Months				Nine Months
	2013		2012		2013		2012
ATC billings to WPL		$24		$22		$72		$67
WPL billings to ATC	2		3		9		7

IPL [Member]

Related Party Transaction [Line Items]

Sales Credited And Purchases Billed

The sales credited to and purchases billed to IPL and WPL for the three and nine months ended September 30 were as follows (in millions):

	IPL								WPL
	Three Months				Nine Months				Three Months				Nine Months
	2013		2012		2013		2012		2013		2012		2013		2012
Sales credited		$2		$3		$5		$7		$3		$4		$10		$10
Purchases billed	108		87		260		237		16		13		44		50

Corporate Services Billings

The amounts billed to IPL and WPL for the three and nine months ended September 30 were as follows (in millions):

	IPL								WPL
	Three Months				Nine Months				Three Months				Nine Months
	2013		2012		2013		2012		2013		2012		2013		2012
Corporate Services billings		$39		$34		$107		$97		$28		$26		$77		$76

Net Intercompany Payables

Net intercompany payables to Corporate Services were as follows (in millions):

	IPL		WPL
	September 30, 2013	December 31, 2012	September 30, 2013	December 31, 2012
Net payables to Corporate Services	$95	$72	$46	$40

WPL [Member]

Related Party Transaction [Line Items]

Sales Credited And Purchases Billed

The sales credited to and purchases billed to IPL and WPL for the three and nine months ended September 30 were as follows (in millions):

	IPL								WPL
	Three Months				Nine Months				Three Months				Nine Months
	2013		2012		2013		2012		2013		2012		2013		2012
Sales credited		$2		$3		$5		$7		$3		$4		$10		$10
Purchases billed	108		87		260		237		16		13		44		50

Corporate Services Billings

The amounts billed to IPL and WPL for the three and nine months ended September 30 were as follows (in millions):

	IPL								WPL
	Three Months				Nine Months				Three Months				Nine Months
	2013		2012		2013		2012		2013		2012		2013		2012
Corporate Services billings		$39		$34		$107		$97		$28		$26		$77		$76

Net Intercompany Payables

Net intercompany payables to Corporate Services were as follows (in millions):

	IPL		WPL
	September 30, 2013	December 31, 2012	September 30, 2013	December 31, 2012
Net payables to Corporate Services	$95	$72	$46	$40

Related Amounts Billed Between Parties

The related amounts billed between the parties for the three and nine months ended September 30 were as follows (in millions):

	Three Months				Nine Months
	2013		2012		2013		2012
ATC billings to WPL		$24		$22		$72		$67
WPL billings to ATC	2		3		9		7