cm:Concept: us-gaap:AssetsSoldUnderAgreementsToRepurchaseRepurchaseLiability
| Assets Sold under Agreements to Repurchase, Repurchase Liability |
| us-gaap:AssetsSoldUnderAgreementsToRepurchaseRepurchaseLiability |
| Amount to be repaid to the counterparty to the repurchase agreement when the carrying amount (or market value, if higher than the carrying amount) of securities or other assets sold under the repurchase agreement exceeds 10 percent of total assets. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:AssetsSoldUnderAgreementsToRepurchaseRepurchaseLiability |