cm:Concept: us-gaap:OwnshareLendingArrangementEarningsPerShareTreatment
| Own-share Lending Arrangement, Earnings Per Share, Treatment |
| us-gaap:OwnshareLendingArrangementEarningsPerShareTreatment |
| Describes the entity's treatment of shares outstanding, in an own-share lending arrangement in contemplation of a convertible debt offering or other financing, for purposes of calculating earnings per share. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:OwnshareLendingArrangementEarningsPerShareTreatment |