cm:Concept: us-gaap:EquitySecuritiesWithoutReadilyDeterminableFairValueFairValueElection
| Equity Securities without Readily Determinable Fair Value, Fair Value Election [true false] |
| us-gaap:EquitySecuritiesWithoutReadilyDeterminableFairValueFairValueElection |
| Indicates (true false) whether measurement method changed to fair value for equity security without readily determinable fair value. |
| cm:Concept |
| Yes/No (xbrli:booleanItemType) |
| As Of (instant) |
| (no balance type) |
| false |
| us-gaap:EquitySecuritiesWithoutReadilyDeterminableFairValueFairValueElection |