cm:Level2TextBlock: us-gaap:ReceivablesTradeAndOtherAccountsReceivableAllowanceForDoubtfulAccountsPolicy
| Receivables, Trade and Other Accounts Receivable, Allowance for Doubtful Accounts, Policy [Policy Text Block] |
| us-gaap:ReceivablesTradeAndOtherAccountsReceivableAllowanceForDoubtfulAccountsPolicy |
| Disclosure of accounting policy for determining the allowance for doubtful accounts for trade and other accounts receivable balances, and when impairments, charge-offs or recoveries are recognized. |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ReceivablesTradeAndOtherAccountsReceivableAllowanceForDoubtfulAccountsPolicy |