cm:Concept: us-gaap:LeveragedLeasesBalanceSheetDeferredTaxesArisingFromLeveragedLeases
| Leveraged Leases, Balance Sheet, Deferred Taxes Arising from Leveraged Leases |
| us-gaap:LeveragedLeasesBalanceSheetDeferredTaxesArisingFromLeveragedLeases |
| The liability for taxes payable in the future as a result of temporary differences in treatment of certain items in the current year arising from the net investment in arrangements meeting the criteria for classification as a leveraged lease. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:LeveragedLeasesBalanceSheetDeferredTaxesArisingFromLeveragedLeases |