cm:Concept: us-gaap:NonmonetaryTransactionFairValueNotDeterminable
| Nonmonetary Transaction, Fair Value Not Determinable |
| us-gaap:NonmonetaryTransactionFairValueNotDeterminable |
| Disclosure of information regarding the volume and type of advertising surrendered and received (such as the number of equivalent pages, the number of minutes, or the overall percentage of advertising volume) when the nonmonetary transaction has no determinable fair value. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:NonmonetaryTransactionFairValueNotDeterminable |