cm:Concept: us-gaap:EquitySecuritiesFvNiChangeInValuationTechnique
| Equity Securities, FV-NI, Change in Valuation Technique [true false] |
| us-gaap:EquitySecuritiesFvNiChangeInValuationTechnique |
| Indicates (true false) whether valuation technique or approach changed for measuring investment in equity security measured at fair value with change in fair value recognized in net income (FV-NI). |
| cm:Concept |
| Yes/No (xbrli:booleanItemType) |
| As Of (instant) |
| (no balance type) |
| false |
| us-gaap:EquitySecuritiesFvNiChangeInValuationTechnique |