cm:Member: us-gaap:UnconditionalPurchaseObligationCategoryOfGoodsOrServicesAcquiredDomain
| Unconditional Purchase Obligation, Category of Goods or Services Acquired [Domain] |
| us-gaap:UnconditionalPurchaseObligationCategoryOfGoodsOrServicesAcquiredDomain |
| General description of the goods or services to be purchased from the counterparty to the unconditional purchase arrangement. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:UnconditionalPurchaseObligationCategoryOfGoodsOrServicesAcquiredDomain |