cm:Concept: us-gaap:DeferredStormAndPropertyReserveDeficiencyCurrent
| Deferred Storm and Property Reserve Deficiency, Current |
| us-gaap:DeferredStormAndPropertyReserveDeficiencyCurrent |
| Carrying amount as of the balance sheet date of capitalized storm costs of a regulated entity that are expected to be recoverable through rate adjustments within one year or the normal operating cycle, if longer. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:DeferredStormAndPropertyReserveDeficiencyCurrent |