cm:Concept: us-gaap:RealizedGainLossOnMarketableSecuritiesCostMethodInvestmentsAndOtherInvestments
| Realized Gain (Loss) on Marketable Securities, Cost Method Investments, and Other Investments |
| us-gaap:RealizedGainLossOnMarketableSecuritiesCostMethodInvestmentsAndOtherInvestments |
| This item represents the total realized gain (loss) included in earnings for the period as a result of selling marketable securities categorized as trading, available-for-sale, or held-to-maturity and any gains or losses realized during the period from the sale of investments accounted for under the cost method of accounting and/or investments that are separately or otherwise not categorized as trading, available-for-sale, or held-to-maturity. Additionally, this item would include any losses recognized for other than temporary impairments (OTTI) of the subject investments in debt and equity securities. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:RealizedGainLossOnMarketableSecuritiesCostMethodInvestmentsAndOtherInvestments |