| Standard label: | Long-term Contract for Purchase of Electric Power [Domain] |
| Name: | us-gaap:LongTermContractForPurchaseOfElectricPowerDomain |
| Documentation: | Name of long-term contract for purchase of electric power. |
| 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:LongTermContractForPurchaseOfElectricPowerDomain |
| Label | Role | Language |
| Long-term Contract for Purchase of Electric Power [Domain] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 980 10 S99 1 (SAB Topic 10.D) | http://fasb.org/us-gaap/role/ref/legacyRef | 980 |