cm:Level2TextBlock: us-gaap:SecuritiesOwnedNotReadilyMarketablePolicy
| Securities Owned Not Readily Marketable, Policy [Policy Text Block] |
| us-gaap:SecuritiesOwnedNotReadilyMarketablePolicy |
| Disclosure of accounting policy for not readily marketable securities, valuation methods and significant assumptions used to determine fair value, restrictions on the investment and reasons investments are not readily marketable, including securities that are not registered, investments in nonpublic entities. |
| cm:Level2TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:SecuritiesOwnedNotReadilyMarketablePolicy |