cm:Concept: us-gaap:AccumulatedOtherComprehensiveIncomeLossBeforeTax1
| AOCI Including Portion Attributable to Noncontrolling Interest, before Tax |
| us-gaap:AccumulatedOtherComprehensiveIncomeLossBeforeTax1 |
| Amount before tax of increase (decrease) in accumulated equity from transactions and other events and circumstances from non-owner sources, including portion attributable to noncontrolling interest. Excludes net income (loss), and accumulated changes in equity from transactions resulting from investments by owners (distributions to owners). |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:AccumulatedOtherComprehensiveIncomeLossBeforeTax1 |