cm:Member: us-gaap:OilAndGasDeliveryCommitmentsAndContractsOilProducingPropertyDomain
| Oil and Gas Delivery Commitments and Contracts, Oil Producing Property [Domain] |
| us-gaap:OilAndGasDeliveryCommitmentsAndContractsOilProducingPropertyDomain |
| Location or source of oil or gas to be used as primary supply point to meet the existing contract or commitment. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:OilAndGasDeliveryCommitmentsAndContractsOilProducingPropertyDomain |