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Related Parties | 3 Months Ended
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Mar. 31, 2019
Related Party Transactions [Line Items] |
Related Parties | RELATED PARTIES Service Agreements - Pursuant to service agreements, 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 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
| 2019 |  | 2018 |  | 2019 |  | 2018
Corporate Services billings |  | $43 |  |  |  | $41 |  |  |  | $33 |  |  |  | $33 |
Sales credited | 15 |  |  | 5 |  |  | 1 |  |  | 1 |
Purchases billed | 84 |  |  | 93 |  |  | 30 |  |  | 17 |
Net intercompany payables to Corporate Services were as follows (in millions):
| IPL |  | WPL
| March 31, 2019 |  | December 31, 2018 |  | March 31, 2019 |  | December 31, 2018
Net payables to Corporate Services | $98 |  | $95 |  | $73 |  | $71
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):
| Three Months
| 2019 |  | 2018
ATC billings to WPL |  | $27 |  |  |  | $27 |
WPL billings to ATC | 4 |  |  | 2 |
WPL owed ATC net amounts of $7 million as of March 31, 2019 and $8 million as of December 31, 2018. WPL’s Sheboygan Falls Energy Facility Lease - Refer to Note 7 for discussion of WPL’s Sheboygan Falls Energy Facility lease.
IPL [Member] |
Related Party Transactions [Line Items] |
Related Parties | RELATED PARTIES Service Agreements - Pursuant to service agreements, 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 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
| 2019 |  | 2018 |  | 2019 |  | 2018
Corporate Services billings |  | $43 |  |  |  | $41 |  |  |  | $33 |  |  |  | $33 |
Sales credited | 15 |  |  | 5 |  |  | 1 |  |  | 1 |
Purchases billed | 84 |  |  | 93 |  |  | 30 |  |  | 17 |
Net intercompany payables to Corporate Services were as follows (in millions):
| IPL |  | WPL
| March 31, 2019 |  | December 31, 2018 |  | March 31, 2019 |  | December 31, 2018
Net payables to Corporate Services | $98 |  | $95 |  | $73 |  | $71
WPL [Member] |
Related Party Transactions [Line Items] |
Related Parties | RELATED PARTIES Service Agreements - Pursuant to service agreements, 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 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
| 2019 |  | 2018 |  | 2019 |  | 2018
Corporate Services billings |  | $43 |  |  |  | $41 |  |  |  | $33 |  |  |  | $33 |
Sales credited | 15 |  |  | 5 |  |  | 1 |  |  | 1 |
Purchases billed | 84 |  |  | 93 |  |  | 30 |  |  | 17 |
Net intercompany payables to Corporate Services were as follows (in millions):
| IPL |  | WPL
| March 31, 2019 |  | December 31, 2018 |  | March 31, 2019 |  | December 31, 2018
Net payables to Corporate Services | $98 |  | $95 |  | $73 |  | $71
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):
| Three Months
| 2019 |  | 2018
ATC billings to WPL |  | $27 |  |  |  | $27 |
WPL billings to ATC | 4 |  |  | 2 |
WPL owed ATC net amounts of $7 million as of March 31, 2019 and $8 million as of December 31, 2018. WPL’s Sheboygan Falls Energy Facility Lease - Refer to Note 7 for discussion of WPL’s Sheboygan Falls Energy Facility lease.

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- Definition Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table. + References No definition available. + Details
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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 -URI http://asc.fasb.org/topic&trid=2122745 + Details
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