cm:Level3TextBlock: us-gaap:ScheduleOfCashCashEquivalentsAndShortTermInvestmentsTableTextBlock
| Cash, Cash Equivalents and Investments [Table Text Block] |
| us-gaap:ScheduleOfCashCashEquivalentsAndShortTermInvestmentsTableTextBlock |
| Tabular disclosure of the components of cash, cash equivalents, and investments. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ScheduleOfCashCashEquivalentsAndShortTermInvestmentsTableTextBlock |
| CashAndCashEquivalentsDetails |