| Standard label: | Federal Income Tax Note [Table Text Block] |
| Name: | us-gaap:FederalIncomeTaxNoteTextBlock |
| Documentation: | Tabular disclosure of the federal tax basis of investment holdings. This item captures the aggregate cost of securities, aggregate gross unrealized appreciation for all securities in which there is an excess of value over tax cost, aggregate gross unrealized depreciation for all securities in which there is an excess of tax cost over value, net unrealized appreciation (depreciation), and an explanation of the differences between tax and book. |
| Object type: | cm:Level3TextBlock |
| 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:FederalIncomeTaxNoteTextBlock |
| Label | Role | Language |
| Federal Income Tax Note [Table Text Block] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 946 320 S99 1 (SX 210.12-12) | http://fasb.org/us-gaap/role/ref/legacyRef | 946 |
| FASB Accounting Standards Codification 946 320 S99 4 (SX 210.12-12C) | http://fasb.org/us-gaap/role/ref/legacyRef | 946 |
| FASB Accounting Standards Codification 946 320 S99 5 (SX 210.12-13) | http://fasb.org/us-gaap/role/ref/legacyRef | 946 |