cm:Level3TextBlock: us-gaap:ScheduleOfOtherNonoperatingIncomeByComponentTextBlock
| Schedule of Other Nonoperating Income, by Component [Table Text Block] |
| us-gaap:ScheduleOfOtherNonoperatingIncomeByComponentTextBlock |
| Tabular disclosure of the detailed components of other nonoperating income. May include methodology, assumptions and amounts for: (a) dividends, (b) interest on securities, (c) profits on securities (net of losses), and (d) miscellaneous other income items. |
| cm:Level3TextBlock |
| Text Block (HTML) (nonnum:textBlockItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:ScheduleOfOtherNonoperatingIncomeByComponentTextBlock |