cm:Concept: us-gaap:IncreaseDecreaseInRestrictedCashAndInvestments
| Increase (Decrease) in Restricted Cash and Investments |
| us-gaap:IncreaseDecreaseInRestrictedCashAndInvestments |
| The net cash inflow or outflow during the period for the aggregate increase (decrease) associated with funds and investments that are not available for withdrawal or use (such as assets held in escrow or contractually limited as to use or disposition) and are associated with underlying transactions that are classified as investing activities. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Credit |
| false |
| us-gaap:IncreaseDecreaseInRestrictedCashAndInvestments |