cm:Concept: us-gaap:NoncontrollingInterestInNetIncomeLossOtherNoncontrollingInterestsNonredeemable
| Noncontrolling Interest in Net Income (Loss) Other Noncontrolling Interests, Nonredeemable |
| us-gaap:NoncontrollingInterestInNetIncomeLossOtherNoncontrollingInterestsNonredeemable |
| Amount after tax of income (loss) attributable to other nonredeemable noncontrolling equity holder. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:NoncontrollingInterestInNetIncomeLossOtherNoncontrollingInterestsNonredeemable |