| Standard label: | Transmission Service Agreement [Member] |
| Name: | us-gaap:TransmissionServiceAgreementMember |
| Documentation: | Agreement between a transmission customer and the transmission provider for service. |
| Object type: | cm:Member |
| Data type: | [Member] (nonnum:domainItemType) |
| Period type: | For Period (duration) |
| Balance type: | (no balance type) |
| Abstract: | true |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:TransmissionServiceAgreementMember |
| Label | Role | Language |
| Transmission Service Agreement [Member] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 350 30 50 2 (a) | http://fasb.org/us-gaap/role/ref/legacyRef | 350 |