cm:Member: us-gaap:FinancialAssetsSoldUnderAgreementToRepurchaseMember
| Financial Assets Sold under Agreement to Repurchase [Member] |
| us-gaap:FinancialAssetsSoldUnderAgreementToRepurchaseMember |
| Agreement under which the transferor transfers a financial asset to a transferee in exchange for cash and concurrently agrees to reacquire that financial asset at a future date. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:FinancialAssetsSoldUnderAgreementToRepurchaseMember |