cm:Level2TextBlock: us-gaap:TradeAndLoanReceivablesNonmortgageLoansHeldForSalePolicyPolicyTextBlock
| Nonmortgage Loan Held-for-sale [Policy Text Block] |
| us-gaap:TradeAndLoanReceivablesNonmortgageLoansHeldForSalePolicyPolicyTextBlock |
| Disclosure of accounting policy for determining the lower of cost or fair value of nonmortgage loans held for sale (that is, aggregate or individual asset basis). |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:TradeAndLoanReceivablesNonmortgageLoansHeldForSalePolicyPolicyTextBlock |