cm:Concept: us-gaap:UtilitiesOperatingExpenseMaintenanceOperationsAndOtherCostsAndExpenses
| Utilities Operating Expense, Maintenance, Operations, and Other Costs and Expenses |
| us-gaap:UtilitiesOperatingExpenseMaintenanceOperationsAndOtherCostsAndExpenses |
| The amount of operating expenses for the period that are associated with the utility's normal revenue producing operation; including selling, general, and administrative expenses, costs incurred for routine plant repairs and maintenance, and operations. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:UtilitiesOperatingExpenseMaintenanceOperationsAndOtherCostsAndExpenses |