cm:Concept: us-gaap:CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption
| Cumulative Effect of New Accounting Principle in Period of Adoption |
| us-gaap:CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption |
| Amount after tax of increase (decrease) to equity or (increase) decrease to net assets, resulting from the cumulative effect adjustment of a new accounting principle applied in the period of adoption. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:CumulativeEffectOfNewAccountingPrincipleInPeriodOfAdoption |