| Standard label: | Accumulated Gain (Loss), Financial Liability, Fair Value Option, Including Portion Attributable to Noncontrolling Interest [Member] |
| Name: | us-gaap:AccumulatedGainLossFinancialLiabilityFairValueOptionIncludingPortionAttributableToNoncontrollingInterestMember |
| Documentation: | Accumulated other comprehensive income (loss) from increase (decrease) in instrument-specific credit risk of financial liability measured under fair value option, including portion attributable to noncontrolling interest. |
| Object type: | cm:Member |
| Data type: | [Member] (nonnum:domainItemType) |
| Period type: | For Period (duration) |
| Balance type: | (no balance type) |
| Abstract: | true |
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:AccumulatedGainLossFinancialLiabilityFairValueOptionIncludingPortionAttributableToNoncontrollingInterestMember |
| Label | Role | Language |
| Accumulated Gain (Loss), Financial Liability, Fair Value Option, Including Portion Attributable to Noncontrolling Interest [Member] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 220 10 45 17B | http://www.xbrl.org/2003/role/disclosureRef | 220 |
| FASB Accounting Standards Codification 220 10 45 10A (l) | http://www.xbrl.org/2003/role/disclosureRef | 220 |
| FASB Accounting Standards Codification 220 10 45 14A | http://www.xbrl.org/2003/role/disclosureRef | 220 |
| FASB Accounting Standards Codification 810 10 50 1A (c)(3) | http://www.xbrl.org/2003/role/disclosureRef | 810 |