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Related Parties | 3 Months Ended
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Mar. 31, 2016
Related Party Transactions [Line Items] |
Related Parties | RELATED PARTIES Service Agreements - IPL and WPL are parties to service agreements with an affiliate, Corporate Services. Pursuant to these service agreements, IPL and WPL receive various administrative and general 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 and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases for the three months ended March 31 were as follows (in millions):
| IPL |  | WPL
| 2016 |  | 2015 |  | 2016 |  | 2015
Corporate Services billings |  | $38 |  |  |  | $36 |  |  |  | $33 |  |  |  | $28 |
Sales credited | 1 |  |  | 4 |  |  | 1 |  |  | 6 |
Purchases billed | 96 |  |  | 79 |  |  | 19 |  |  | 14 |
Net intercompany payables to Corporate Services were as follows (in millions):
| IPL |  | WPL
| March 31, 2016 |  | December 31, 2015 |  | March 31, 2016 |  | December 31, 2015
Net payables to Corporate Services | $100 |  | $93 |  | $59 |  | $54
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):
| 2016 |  | 2015
ATC billings to WPL |  | $27 |  |  |  | $25 |
WPL billings to ATC | 3 |  |  | 2 |
WPL owed ATC net amounts of $8 million as of March 31, 2016 and $8 million as of December 31, 2015.
IPL [Member] |
Related Party Transactions [Line Items] |
Related Parties | RELATED PARTIES Service Agreements - IPL and WPL are parties to service agreements with an affiliate, Corporate Services. Pursuant to these service agreements, IPL and WPL receive various administrative and general 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 and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases for the three months ended March 31 were as follows (in millions):
| IPL |  | WPL
| 2016 |  | 2015 |  | 2016 |  | 2015
Corporate Services billings |  | $38 |  |  |  | $36 |  |  |  | $33 |  |  |  | $28 |
Sales credited | 1 |  |  | 4 |  |  | 1 |  |  | 6 |
Purchases billed | 96 |  |  | 79 |  |  | 19 |  |  | 14 |
Net intercompany payables to Corporate Services were as follows (in millions):
| IPL |  | WPL
| March 31, 2016 |  | December 31, 2015 |  | March 31, 2016 |  | December 31, 2015
Net payables to Corporate Services | $100 |  | $93 |  | $59 |  | $54
WPL [Member] |
Related Party Transactions [Line Items] |
Related Parties | RELATED PARTIES Service Agreements - IPL and WPL are parties to service agreements with an affiliate, Corporate Services. Pursuant to these service agreements, IPL and WPL receive various administrative and general 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 and benefits, fees associated with various professional services, depreciation and amortization of property, plant and equipment, and a return on net assets. Corporate Services also acts as agent on behalf of IPL and WPL pursuant to the service agreements. As agent, Corporate Services enters into energy, capacity, ancillary services, and transmission sale and purchase transactions within MISO. Corporate Services assigns such sales and purchases among IPL and WPL based on statements received from MISO. The amounts billed for services provided, sales credited and purchases for the three months ended March 31 were as follows (in millions):
| IPL |  | WPL
| 2016 |  | 2015 |  | 2016 |  | 2015
Corporate Services billings |  | $38 |  |  |  | $36 |  |  |  | $33 |  |  |  | $28 |
Sales credited | 1 |  |  | 4 |  |  | 1 |  |  | 6 |
Purchases billed | 96 |  |  | 79 |  |  | 19 |  |  | 14 |
Net intercompany payables to Corporate Services were as follows (in millions):
| IPL |  | WPL
| March 31, 2016 |  | December 31, 2015 |  | March 31, 2016 |  | December 31, 2015
Net payables to Corporate Services | $100 |  | $93 |  | $59 |  | $54
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):
| 2016 |  | 2015
ATC billings to WPL |  | $27 |  |  |  | $25 |
WPL billings to ATC | 3 |  |  | 2 |
WPL owed ATC net amounts of $8 million as of March 31, 2016 and $8 million as of December 31, 2015.

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- Definition The entire disclosure for related party transactions. Examples of related party transactions include transactions between (a) a parent company and its subsidiary; (b) subsidiaries of a common parent; (c) and entity and its principal owners; and (d) affiliates. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 3 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39603-107864 Reference 2: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 4 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39622-107864 Reference 3: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 1 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39549-107864 Reference 4: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 5 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39678-107864 Reference 5: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 850 -SubTopic 10 -Section 50 -Paragraph 6 -URI http://asc.fasb.org/extlink&oid=6457730&loc=d3e39691-107864 Reference 6: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 235 -SubTopic 10 -Section S99 -Paragraph 1 -Subparagraph (SX 210.4-08.(k)) -URI http://asc.fasb.org/extlink&oid=26873400&loc=d3e23780-122690 Reference 7: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 04 -Paragraph b -Article 3A Reference 8: http://www.xbrl.org/2003/role/presentationRef -Publisher SEC -Name Regulation S-X (SX) -Number 210 -Section 08 -Paragraph k -Article 4 + Details
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