cm:Concept: us-gaap:SecuritiesReceivedAsCollateralAmountRepledgedAndSold
| Securities Received as Collateral, Amount Repledged and Sold |
| us-gaap:SecuritiesReceivedAsCollateralAmountRepledgedAndSold |
| The fair value of collateral received that has been sold or re-pledged and is owed to the debtor (transferor) upon settlement of the related contractual obligation under which it was received. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:SecuritiesReceivedAsCollateralAmountRepledgedAndSold |