| Standard label: | Income Tax, Policy [Policy Text Block] |
| Name: | us-gaap:IncomeTaxPolicyTextBlock |
| Documentation: | Disclosure of accounting policy for income taxes, which may include its accounting policies for recognizing and measuring deferred tax assets and liabilities and related valuation allowances, recognizing investment tax credits, operating loss carryforwards, tax credit carryforwards, and other carryforwards, methodologies for determining its effective income tax rate and the characterization of interest and penalties in the financial statements. |
| 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:IncomeTaxPolicyTextBlock |
| Label | Role | Language |
| Income Tax, Policy [Policy Text Block] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 220 10 50 1 | http://www.xbrl.org/2003/role/disclosureRef | 220 |
| FASB Accounting Standards Codification 235 10 50 3 | http://fasb.org/us-gaap/role/ref/legacyRef | 235 |
| FASB Accounting Standards Codification 740 10 50 17 (b) | http://fasb.org/us-gaap/role/ref/legacyRef | 740 |
| FASB Accounting Standards Codification 740 10 50 19 | http://fasb.org/us-gaap/role/ref/legacyRef | 740 |
| FASB Accounting Standards Codification 740 10 50 20 | http://www.xbrl.org/2003/role/disclosureRef | 740 |
| FASB Accounting Standards Codification 740 10 45 25 | http://fasb.org/us-gaap/role/ref/legacyRef | 740 |
| FASB Accounting Standards Codification 740 10 45 28 | http://fasb.org/us-gaap/role/ref/legacyRef | 740 |
| FASB Accounting Standards Codification 740 30 05 1 | http://fasb.org/us-gaap/role/ref/legacyRef | 740 |
| FASB Accounting Standards Codification 954 740 50 1 | http://fasb.org/us-gaap/role/ref/legacyRef | 954 |