cm:Concept: us-gaap:DerivativeAssetNotOffsetPolicyElectionDeduction
| Derivative Asset, Not Offset, Policy Election Deduction |
| us-gaap:DerivativeAssetNotOffsetPolicyElectionDeduction |
| Fair value of financial asset or other contract with one or more underlyings, notional amount or payment provision or both, and the contract can be net settled by means outside the contract or delivery of an asset, elected not to be offset, deducted from derivative assets. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:DerivativeAssetNotOffsetPolicyElectionDeduction |