| Standard label: | Net Regulatory Assets |
| Name: | us-gaap:NetRegulatoryAssets |
| Documentation: | The net amount of all regulatory assets less all regulatory liabilities as of the end of the period. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | As Of (instant) |
| Balance type: | Debit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:NetRegulatoryAssets |
| Label | Role | Language |
| Net Regulatory Assets | http://www.xbrl.org/2003/role/label | en-US |
| Net Regulatory Assets, Total | http://www.xbrl.org/2003/role/totalLabel | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 980 340 50 1 | http://fasb.org/us-gaap/role/ref/legacyRef | 980 |