cm:Concept: us-gaap:TaxCutsAndJobsActOf2017DecreaseInDeferredTaxLiabilityDueToTransitionTax
| Tax Cuts and Jobs Act, Decrease in Deferred Tax Liability due to Transition Tax |
| us-gaap:TaxCutsAndJobsActOf2017DecreaseInDeferredTaxLiabilityDueToTransitionTax |
| Amount of decrease in deferred tax liability previously recognized attributable to taxable temporary differences from undistributed earnings of foreign subsidiary and other recognized entity now subject to transition tax. |
| cm:Concept |
| Monetary (xbrli:monetaryItemType) |
| For Period (duration) |
| Debit |
| false |
| us-gaap:TaxCutsAndJobsActOf2017DecreaseInDeferredTaxLiabilityDueToTransitionTax |