| Standard label: | Environmental Costs, Policy [Policy Text Block] |
| Name: | us-gaap:EnvironmentalCostsPolicy |
| Documentation: | Disclosure of accounting policy for obligations that resulted from improper or other-than normal operation of a long-lived asset in the past. This accounting policy may address (1) whether the related remediation costs are expensed or capitalized, (2) whether the obligation is measured on a discounted basis, (3) the event, situation, or set of circumstances that generally triggers recognition of loss contingencies arising from the entity's environmental remediation-related obligations, and (4) the timing of recognition of any recoveries. |
| Object type: | cm:Level2TextBlock |
| Data type: | Text Block (HTML) (nonnum:textBlockItemType) |
| Period type: | For Period (duration) |
| Balance type: | (no balance type) |
| Abstract: | false |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:EnvironmentalCostsPolicy |
| Label | Role | Language |
| Environmental Costs, Policy [Policy Text Block] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 235 10 50 3 | http://fasb.org/us-gaap/role/ref/legacyRef | 235 |
| FASB Accounting Standards Codification 410 30 50 4 | http://fasb.org/us-gaap/role/ref/legacyRef | 410 |
| FASB Accounting Standards Codification 410 30 50 8 | http://fasb.org/us-gaap/role/ref/legacyRef | 410 |
| FASB Accounting Standards Codification 410 30 | http://fasb.org/us-gaap/role/ref/legacyRef | 410 |
| FASB Accounting Standards Codification 410 30 55 14 | http://fasb.org/us-gaap/role/ref/legacyRef | 410 |