cm:Concept: us-gaap:DerivativeUnderlyingBasis
| Derivative, Underlying Basis |
| us-gaap:DerivativeUnderlyingBasis |
| Reference to the index or unit of measurement for the underlying which establishes the pricing terms of the derivative instrument. For example, the basis on the underlying for a natural gas futures contract might be the NYMEX price per million British thermal units (MMBtu). |
| cm:Concept |
| Text/String (xbrli:stringItemType) |
| For Period (duration) |
| (no balance type) |
| false |
| us-gaap:DerivativeUnderlyingBasis |