Related Parties

3 Months Ended

Mar. 31, 2013

Related Party Transaction [Line Items]

Related Parties

RELATED PARTIES

System Coordination and Operating Agreement - IPL and WPL are parties to a system coordination and operating agreement whereby Corporate Services serves as agent on behalf of IPL and WPL. The agreement, which has been approved or reviewed by the Federal Energy Regulatory Commission (FERC) and all state regulatory bodies having jurisdiction, provides a contractual basis for coordinated planning, construction, operation and maintenance of the interconnected electric generation systems of IPL and WPL. As agent of the agreement, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions. Corporate Services allocates such sales and purchases among IPL and WPL based on procedures included in the agreement. The sales credited to and purchases billed to IPL and WPL for the three months ended March 31 were as follows (in millions):

	IPL				WPL
	2013		2012		2013		2012
Sales credited		$2		$2		$3		$2
Purchases billed	76		72		14		24

Service Agreement - Pursuant to a service agreement, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation, benefits, fees associated with various professional services and a return on net assets. The amounts billed to IPL and WPL for the three months ended March 31 were as follows (in millions):

	IPL				WPL
	2013		2012		2013		2012
Corporate Services billings		$32		$29		$26		$23

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

	IPL		WPL
	March 31, 2013	December 31, 2012	March 31, 2013	December 31, 2012
Net payables to Corporate Services	$79	$72	$42	$40

ATC - Pursuant to various agreements, WPL receives a range of transmission services from ATC. WPL provides operation, maintenance, and construction services to ATC. WPL and ATC also bill each other for use of shared facilities owned by each party. The related amounts billed between the parties for the three months ended March 31 were as follows (in millions):

	2013		2012
ATC billings to WPL		$24		$22
WPL billings to ATC	3		2

WPL owed ATC net amounts of $7 million as of March 31, 2013 and $6 million as of December 31, 2012.

IPL [Member]

Related Party Transaction [Line Items]

Related Parties

RELATED PARTIES

System Coordination and Operating Agreement - IPL and WPL are parties to a system coordination and operating agreement whereby Corporate Services serves as agent on behalf of IPL and WPL. The agreement, which has been approved or reviewed by the Federal Energy Regulatory Commission (FERC) and all state regulatory bodies having jurisdiction, provides a contractual basis for coordinated planning, construction, operation and maintenance of the interconnected electric generation systems of IPL and WPL. As agent of the agreement, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions. Corporate Services allocates such sales and purchases among IPL and WPL based on procedures included in the agreement. The sales credited to and purchases billed to IPL and WPL for the three months ended March 31 were as follows (in millions):

	IPL				WPL
	2013		2012		2013		2012
Sales credited		$2		$2		$3		$2
Purchases billed	76		72		14		24

Service Agreement - Pursuant to a service agreement, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation, benefits, fees associated with various professional services and a return on net assets. The amounts billed to IPL and WPL for the three months ended March 31 were as follows (in millions):

	IPL				WPL
	2013		2012		2013		2012
Corporate Services billings		$32		$29		$26		$23

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

	IPL		WPL
	March 31, 2013	December 31, 2012	March 31, 2013	December 31, 2012
Net payables to Corporate Services	$79	$72	$42	$40

ATC - Pursuant to various agreements, WPL receives a range of transmission services from ATC. WPL provides operation, maintenance, and construction services to ATC. WPL and ATC also bill each other for use of shared facilities owned by each party. The related amounts billed between the parties for the three months ended March 31 were as follows (in millions):

	2013		2012
ATC billings to WPL		$24		$22
WPL billings to ATC	3		2

WPL owed ATC net amounts of $7 million as of March 31, 2013 and $6 million as of December 31, 2012.

WPL [Member]

Related Party Transaction [Line Items]

Related Parties

RELATED PARTIES

System Coordination and Operating Agreement - IPL and WPL are parties to a system coordination and operating agreement whereby Corporate Services serves as agent on behalf of IPL and WPL. The agreement, which has been approved or reviewed by the Federal Energy Regulatory Commission (FERC) and all state regulatory bodies having jurisdiction, provides a contractual basis for coordinated planning, construction, operation and maintenance of the interconnected electric generation systems of IPL and WPL. As agent of the agreement, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions. Corporate Services allocates such sales and purchases among IPL and WPL based on procedures included in the agreement. The sales credited to and purchases billed to IPL and WPL for the three months ended March 31 were as follows (in millions):

	IPL				WPL
	2013		2012		2013		2012
Sales credited		$2		$2		$3		$2
Purchases billed	76		72		14		24

Service Agreement - Pursuant to a service agreement, IPL and WPL receive various administrative and general services from an affiliate, Corporate Services. These services are billed to IPL and WPL at cost based on expenses incurred by Corporate Services for the benefit of IPL and WPL, respectively. These costs consisted primarily of employee compensation, benefits, fees associated with various professional services and a return on net assets. The amounts billed to IPL and WPL for the three months ended March 31 were as follows (in millions):

	IPL				WPL
	2013		2012		2013		2012
Corporate Services billings		$32		$29		$26		$23

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

	IPL		WPL
	March 31, 2013	December 31, 2012	March 31, 2013	December 31, 2012
Net payables to Corporate Services	$79	$72	$42	$40

ATC - Pursuant to various agreements, WPL receives a range of transmission services from ATC. WPL provides operation, maintenance, and construction services to ATC. WPL and ATC also bill each other for use of shared facilities owned by each party. The related amounts billed between the parties for the three months ended March 31 were as follows (in millions):

	2013		2012
ATC billings to WPL		$24		$22
WPL billings to ATC	3		2

WPL owed ATC net amounts of $7 million as of March 31, 2013 and $6 million as of December 31, 2012.