cm:Concept: us-gaap:ContractWithCustomerRefundLiabilityNoncurrent
| Contract with Customer, Refund Liability, Noncurrent |
| us-gaap:ContractWithCustomerRefundLiabilityNoncurrent |
| Amount of liability for consideration received or receivable from customer which is not included in transaction price, when consideration is expected to be refunded to customer, classified as noncurrent. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:ContractWithCustomerRefundLiabilityNoncurrent |