cm:Concept: us-gaap:DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedGross
| Derivative Asset, Securities Purchased under Agreements to Resell, Securities Borrowed, Gross |
| us-gaap:DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedGross |
| Amount, before effects of master netting arrangements, of derivative assets, securities purchased under agreements to resell and securities borrowed. Includes assets elected not to be offset. Excludes assets not subject to a master netting arrangement. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Debit |
| false |
| us-gaap:DerivativeAssetSecuritiesPurchasedUnderAgreementsToResellSecuritiesBorrowedGross |