| Standard label: | Retirement Plan Type [Axis] |
| Name: | us-gaap:RetirementPlanTypeAxis |
| Documentation: | Information by type of retirement benefit plan. Includes, but is not limited to, retirement benefit arrangement for defined benefit pension and other postretirement plans, retirement benefit arrangement for defined contribution pension and other postretirement plans, and special and contractual termination benefits payable upon retirement. |
| Object type: | cm:Axis |
| Data type: | Text/String (xbrli:stringItemType) |
| Period type: | For Period (duration) |
| Balance type: | (no balance type) |
| Abstract: | true |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:RetirementPlanTypeAxis |
| Label | Role | Language |
| Retirement Plan Type [Axis] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 712 10 15 4 (c) | http://fasb.org/us-gaap/role/ref/legacyRef | 712 |
| FASB Accounting Standards Codification 712 10 15 4 (d) | http://fasb.org/us-gaap/role/ref/legacyRef | 712 |
| FASB Accounting Standards Codification 715 20 50 1 | http://fasb.org/us-gaap/role/ref/legacyRef | 715 |
| FASB Accounting Standards Codification 715 20 50 2 | http://fasb.org/us-gaap/role/ref/legacyRef | 715 |
| FASB Accounting Standards Codification 715 70 50 1 | http://fasb.org/us-gaap/role/ref/legacyRef | 715 |