cm:Concept: us-gaap:UnrecordedUnconditionalPurchaseObligationChangeOfAmountAsResultOfVariableComponents
| Unrecorded Unconditional Purchase Obligation, Change of Amount as Result of Variable Components |
| us-gaap:UnrecordedUnconditionalPurchaseObligationChangeOfAmountAsResultOfVariableComponents |
| Amount of change that payments under a contractual obligation might vary as facts and circumstances change. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:UnrecordedUnconditionalPurchaseObligationChangeOfAmountAsResultOfVariableComponents |