cm:Concept: us-gaap:IncomeTaxEffectsAllocatedDirectlyToEquityEquityTransactions
| Income Tax Effects Allocated Directly to Equity, Equity Transactions |
| us-gaap:IncomeTaxEffectsAllocatedDirectlyToEquityEquityTransactions |
| The tax effect of an increase or decrease in contributed capital (for example, deductible expenditures reported as a reduction of the proceeds from issuing capital stock) during the period charged or credited directly to shareholders' equity. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:IncomeTaxEffectsAllocatedDirectlyToEquityEquityTransactions |