cm:Member: us-gaap:WrittenLoanCommitmentFairValueOptionMember
| Written Loan Commitment, Fair Value Option [Member] |
| us-gaap:WrittenLoanCommitmentFairValueOptionMember |
| This element represents a written loan commitment that would otherwise not be recognized in the issuers or borrowers financial statements as the loan has not yet been funded, but which meets the definition of a financial asset or liability for eligibility of applying the fair value option. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:WrittenLoanCommitmentFairValueOptionMember |