| Standard label: | Revenue Recognition, Real Estate Transactions, Policy [Policy Text Block] |
| Name: | us-gaap:RevenueRecognitionRealEstateTransactionsPolicy |
| Documentation: | Disclosure of accounting policy for the timing and amount of revenue recognized on transfers of real estate, excluding retail land sales. The entity also may disclose its treatment of any unearned or deferred revenue that arises from the transaction. |
| 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:RevenueRecognitionRealEstateTransactionsPolicy |
| Label | Role | Language |
| Revenue Recognition, Real Estate Transactions, 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/otherTransitionRef | 235 |
| FASB Accounting Standards Codification 360 20 40 7 | http://fasb.org/us-gaap/role/ref/otherTransitionRef | 360 |
| FASB Accounting Standards Codification 360 20 40 28 | http://fasb.org/us-gaap/role/ref/otherTransitionRef | 360 |
| FASB Accounting Standards Codification 970 605 05 1 | http://fasb.org/us-gaap/role/ref/otherTransitionRef | 970 |