cm:Concept: us-gaap:DebtorReorganizationItemsNetGainLossOnRejectionOfLeasesAndOtherExecutoryContracts1
| Debtor Reorganization Items, Net Gain (Loss) on Rejection of Leases and Other Executory Contracts |
| us-gaap:DebtorReorganizationItemsNetGainLossOnRejectionOfLeasesAndOtherExecutoryContracts1 |
| Amount of gain (loss) on rejection of leases and other executory contracts, reported as a reorganization item. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:DebtorReorganizationItemsNetGainLossOnRejectionOfLeasesAndOtherExecutoryContracts1 |