cm:Concept: us-gaap:GainLossOnSaleOfEquityInvestments
| Gain (Loss) on Sale of Equity Investments |
| us-gaap:GainLossOnSaleOfEquityInvestments |
| The difference between the carrying value and the sale price of equity securities, not separately or otherwise categorized as trading or available-for-sale. This element includes investments in which the entity holds a small ownership stake (generally, less than 20% of the shares outstanding) and cannot exert significant influence. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:GainLossOnSaleOfEquityInvestments |