cm:Member: us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember
| Accumulated Gain (Loss), Net, Cash Flow Hedge, Parent [Member] |
| us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember |
| Accumulated other comprehensive income (loss) from gain (loss) of derivative instrument designated and qualifying as cash flow hedge included in assessment of hedge effectiveness, attributable to parent. |
| cm:Member |
| [Member] (nonnum:domainItemType) |
| For Period (duration) |
| (no balance type) |
| true |
| us-gaap:AccumulatedGainLossNetCashFlowHedgeParentMember |