cm:Concept: us-gaap:BusinessCombinationCostOfAcquiredEntityEquityInterestsIssuedAndIssuableFairValueMethod
| Business Combination, Consideration Transferred, Equity Interests Issued and Issuable Fair Value Method |
| us-gaap:BusinessCombinationCostOfAcquiredEntityEquityInterestsIssuedAndIssuableFairValueMethod |
| The method of determining the fair value of the equity interests of the acquirer, including the number of instruments or interests issued or issuable in consideration for the business combination. |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:BusinessCombinationCostOfAcquiredEntityEquityInterestsIssuedAndIssuableFairValueMethod |