cm:Concept: us-gaap:SharesSubjectToMandatoryRedemptionSettlementTermsExcessOfAssetsOverLiabilities
| Financial Instruments Subject to Mandatory Redemption, Settlement Terms, Excess of Assets over Liabilities |
| us-gaap:SharesSubjectToMandatoryRedemptionSettlementTermsExcessOfAssetsOverLiabilities |
| The value of the excess of assets over liabilities. If all outstanding shares are subject to mandatory redemption and the redemption price is less than the book value (the redemption price is less than the company's equity balance), the resulting cumulative transition adjustment and subsequent adjustments to reflect changes in the redemption price of the shares are recorded as an excess of assets over liabilities (equity). |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:SharesSubjectToMandatoryRedemptionSettlementTermsExcessOfAssetsOverLiabilities |