cm:Concept: us-gaap:NewAccountingPronouncementOrChangeInAccountingPrincipleRetrospectiveApplicationImpracticable
| New Accounting Pronouncement or Change in Accounting Principle, Retrospective Application Impracticable |
| us-gaap:NewAccountingPronouncementOrChangeInAccountingPrincipleRetrospectiveApplicationImpracticable |
| Description of why retrospective application is impracticable and the alternative method used to report the change in accounting principle. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:NewAccountingPronouncementOrChangeInAccountingPrincipleRetrospectiveApplicationImpracticable |