| Regulatory Assets and Liabilities, Recognition Criteria |
| us-gaap:RegulatoryAssetsAndLiabilitiesRecognitionCriteria |
| Describes the entity's criteria for recording regulatory assets and regulatory liabilities only because they are included in the rate-setting process, and rate-related accruals and deferrals, such as amounts receivable from (or due to) customers under fuel adjustment clauses and interim rates collected prior to regulatory approval. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:RegulatoryAssetsAndLiabilitiesRecognitionCriteria |