cm:Concept: us-gaap:AdjustmentForLongTermIntercompanyTransactionsTaxExpenseBenefit
| Adjustment for Long-term Intercompany Transactions, Tax Expense (Benefit) |
| us-gaap:AdjustmentForLongTermIntercompanyTransactionsTaxExpenseBenefit |
| Amount of tax expense (benefit) related to gain (loss) on intercompany foreign currency transactions that are of a long-term-investment nature or settlement is not planned or anticipated in the foreseeable future. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:AdjustmentForLongTermIntercompanyTransactionsTaxExpenseBenefit |