cm:Concept: us-gaap:NewAccountingPronouncementOrChangeInAccountingPrinciplePriorPeriodNotRestated
| New Accounting Pronouncement or Change in Accounting Principle, Prior Period Not Restated [true false] |
| us-gaap:NewAccountingPronouncementOrChangeInAccountingPrinciplePriorPeriodNotRestated |
| Indicates (true false) whether prior period was not restated when there is change in accounting principle or adoption of new accounting pronouncement. Excludes correction of error. |
| cm:Concept |
| Yes/No (xbrli:booleanItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:NewAccountingPronouncementOrChangeInAccountingPrinciplePriorPeriodNotRestated |