cm:Concept: us-gaap:DebtSecuritiesAvailableForSaleCostOfSecurityTransferredMethodExtensibleList
| Debt Securities, Available-for-sale, Cost of Security Transferred, Method [Extensible List] |
| us-gaap:DebtSecuritiesAvailableForSaleCostOfSecurityTransferredMethodExtensibleList |
| Indicates method used to determine cost basis of amount reclassified out of accumulated other comprehensive income (AOCI) into earnings from transfer of investment in debt security measured at fair value with change in fair value recognized in other comprehensive income (available-for-sale) to investment in debt security measured at fair value with changes in fair value recognized in net income (trading). Includes, but is not limited to, specific identification or average cost method. |
| cm:Concept |
| srt-types:extensibleListItemType |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DebtSecuritiesAvailableForSaleCostOfSecurityTransferredMethodExtensibleList |