cm:Level2TextBlock: us-gaap:AllowanceForFundsUsedDuringConstructionPolicy
| Allowance for Funds Used During Construction, Policy [Policy Text Block] |
| us-gaap:AllowanceForFundsUsedDuringConstructionPolicy |
| Disclosure of accounting policy for AFUDC (for example, component of PPE, credit to income statement), information regarding the inclusion in rates (only capitalized if its inclusion in rates is probable) and description of AFUDC (for example, represents the cost of capital used during construction). |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:AllowanceForFundsUsedDuringConstructionPolicy |