cm:Level3TextBlock: us-gaap:NetInvestmentInLeaseAllowanceForCreditLossTableTextBlock
| Net Investment in Lease, Allowance for Credit Loss [Table Text Block] |
| us-gaap:NetInvestmentInLeaseAllowanceForCreditLossTableTextBlock |
| Tabular disclosure of allowance for credit loss on net investment in sales-type and direct financing leases. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:NetInvestmentInLeaseAllowanceForCreditLossTableTextBlock |