cm:Concept: us-gaap:OtherInvestmentNotReadilyMarketableFairValue
| Other Investment Not Readily Marketable, Fair Value |
| us-gaap:OtherInvestmentNotReadilyMarketableFairValue |
| Value of the other investment not readily marketable determined by management based upon fair value methods, including pricing of similar securities and valuation techniques, that was used to record the investment for financial reporting purposes. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:OtherInvestmentNotReadilyMarketableFairValue |