cm:Concept: us-gaap:ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital
| Proceeds from Equity Method Investment, Distribution, Return of Capital |
| us-gaap:ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital |
| Amount of distribution received from equity method investee for return of investment, classified as investing activities. Excludes distribution for return on investment, classified as operating activities. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:ProceedsFromEquityMethodInvestmentDividendsOrDistributionsReturnOfCapital |