cm:Concept: us-gaap:RecordedThirdPartyEnvironmentalRecoveriesDiscount
| Recorded Third-Party Environmental Recoveries, Discount |
| us-gaap:RecordedThirdPartyEnvironmentalRecoveriesDiscount |
| The amount of imputed interest necessary to reduce the expected aggregate undiscounted amount of the asset for third-party recoveries related to environmental remediation obligations to the present value recognized on the balance sheet (if the receivable is discounted). |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| As Of (instant) |
| Credit |
| false |
| us-gaap:RecordedThirdPartyEnvironmentalRecoveriesDiscount |