cm:Concept: us-gaap:ShareBasedGoodsAndNonemployeeServicesTransactionValuationMethodExpectedVolatilityRate
| Share-based Goods and Nonemployee Services Transaction, Valuation Method, Expected Volatility Rate |
| us-gaap:ShareBasedGoodsAndNonemployeeServicesTransactionValuationMethodExpectedVolatilityRate |
| The estimated measure of the percentage amount by which a share price is expected to fluctuate during the expected term of a nonvested share or option award issued to other than an employee. |
| cm:Concept |
| Percent (num:percentItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ShareBasedGoodsAndNonemployeeServicesTransactionValuationMethodExpectedVolatilityRate |