| Standard label: | Schedule of Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities [Table] | 
| Name: | us-gaap:AssumptionForFairValueOnSecuritizationDateOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesTable | 
| Documentation: | Information related to the key inputs and assumptions used in measuring the fair value of assets obtained or liabilities incurred, as the result of a sale of financial assets, relating to the transferor's continuing involvement, if any, at the time of securitization, asset-backed financing arrangement, or similar transfer (including at a minimum, but not limited to, and if applicable, quantitative information about discount rates, expected prepayments including the expected weighted-average life of prepayable financial assets, and anticipated credit losses, including expected static pool losses). | 
| Object type: | cm:Table | 
| Data type: | Text/String (xbrli:stringItemType) | 
| Period type: | For Period (duration) | 
| Balance type: | (no balance type) | 
| Abstract: | true | 
| Workiva Wdesk Taxonomy Analyzer: | us-gaap:AssumptionForFairValueOnSecuritizationDateOfInterestsContinuedToBeHeldByTransferorServicingAssetsOrLiabilitiesTable | 
| Label | Role | Language | 
| Schedule of Fair Value Assumption, Date of Securitization or Asset-backed Financing Arrangement, Transferor's Continuing Involvement, Servicing Assets or Liabilities [Table] | http://www.xbrl.org/2003/role/label | en-US | 
| Reference | Role | Topic | 
| FASB Accounting Standards Codification 860 20 50 3 (c) | http://fasb.org/us-gaap/role/ref/legacyRef | 860 |