cm:Concept: us-gaap:SecuritiesLoanedAmountOffsetAgainstCollateral
| Securities Loaned, Amount Offset Against Collateral |
| us-gaap:SecuritiesLoanedAmountOffsetAgainstCollateral |
| Amount, after effects of master netting arrangements, of securities loaned to entities in exchange for collateral offset against a right to receive collateral. Includes liabilities not subject to a master netting arrangement and not elected to be offset. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:SecuritiesLoanedAmountOffsetAgainstCollateral |