| Standard label: | Short-Duration Contracts, Policy [Policy Text Block] |
| Name: | us-gaap:ShortDurationContractsPolicy |
| Documentation: | Disclosure of accounting policy for short-duration insurance products, which include most property and casualty contracts, certain term life insurance, accident and health contracts, and other contracts not deemed to be of long-duration by virtue of their providing insurance protection for a fixed period of short duration, and rights granted to the insurer with respect to cancellation and premium adjustments; and revenue recognition policies pertaining to premiums received thereon. |
| 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:ShortDurationContractsPolicy |
| Label | Role | Language |
| Short-Duration Contracts, Policy [Policy Text Block] | http://www.xbrl.org/2003/role/label | en-US |
| Reference | Role | Topic |
| FASB Accounting Standards Codification 235 10 50 3 | http://fasb.org/us-gaap/role/ref/legacyRef | 235 |
| FASB Accounting Standards Codification 944 605 25 1 | http://fasb.org/us-gaap/role/ref/legacyRef | 944 |
| FASB Accounting Standards Codification 944 605 25 2 | http://fasb.org/us-gaap/role/ref/legacyRef | 944 |