cm:Level1TextBlock: us-gaap:ShareholdersEquityAndShareBasedPaymentsTextBlock
| Shareholders' Equity and Share-based Payments [Text Block] |
| us-gaap:ShareholdersEquityAndShareBasedPaymentsTextBlock |
| The entire disclosure for shareholders' equity and share-based payment arrangement. Includes, but is not limited to, disclosure of policy and terms of share-based payment arrangement, deferred compensation arrangement, and employee stock purchase plan (ESPP). |
| cm:Level1TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ShareholdersEquityAndShareBasedPaymentsTextBlock |
| ShareholdersEquityAndSharebasedPayments |