cm:Member: us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain
| Exercise Price Range [Domain] |
| us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain |
| Supplementary information on outstanding and exercisable share awards as of the balance sheet date which stratifies outstanding options by ranges of exercise prices. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:ShareBasedCompensationSharesAuthorizedUnderStockOptionPlansExercisePriceRangeDomain |