| Standard label: | Proceeds from Decommissioning Trust Fund Assets |
| Name: | us-gaap:ProceedsFromDecommissioningFund |
| Documentation: | The cash inflow from the sale of assets held in a decommissioning trust fund. |
| Object type: | cm:Concept |
| Data type: | Monetary (xbrli:monetaryItemType) |
| Period type: | For Period (duration) |
| Balance type: | Debit |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:ProceedsFromDecommissioningFund |
| Label | Role | Language |
| Proceeds from Decommissioning Trust Fund Assets | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 230 10 45 12 | http://fasb.org/us-gaap/role/ref/legacyRef | 230 |
| Part Of Roll Up: |
| us-gaap:ProceedsFromSaleMaturityAndCollectionsOfInvestments |