cm:Concept: us-gaap:InterestBearingDomesticDepositLiabilitiesDescription
| Interest-bearing Domestic Deposit Liabilities, Description |
| us-gaap:InterestBearingDomesticDepositLiabilitiesDescription |
| Description of interest-bearing domestic deposit liabilities, which may include methodology, assumptions and the types and amounts of domestic deposit liabilities. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:InterestBearingDomesticDepositLiabilitiesDescription |