cm:Concept: us-gaap:TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets
| Tier One Risk Based Capital Required to be Well Capitalized to Risk Weighted Assets |
| us-gaap:TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets |
| The Tier 1 capital ratio (Tier 1 capital divided by risk weighted assets) required to be categorized as "well capitalized" under the regulatory framework for prompt corrective action. |
| cm:Concept |
| Percent (num:percentItemType) |
| As Of (instant) |
| (no balance type) |
| false |
| us-gaap:TierOneRiskBasedCapitalRequiredToBeWellCapitalizedToRiskWeightedAssets |