cm:Concept: us-gaap:TaxCutsAndJobsActOf2017ReclassificationFromAociToRetainedEarningsTaxEffect
       
          
          | Tax Cuts and Jobs Act, Reclassification from AOCI to Retained Earnings, Tax Effect | 
       
          
          | us-gaap:TaxCutsAndJobsActOf2017ReclassificationFromAociToRetainedEarningsTaxEffect | 
       
          
          | Amount of increase (decrease) in accumulated other comprehensive income (AOCI) for reclassification to retained earnings of tax effect from remeasurement of deferred tax pursuant to Tax Cuts and Jobs Act. | 
       
          
          | cm:Concept | 
       
          
          | Monetary (xbrli:monetaryItemType) | 
       
          
          | For Period (duration) | 
       
          
          | Credit | 
       
          
          | false | 
       
          
          | us-gaap:TaxCutsAndJobsActOf2017ReclassificationFromAociToRetainedEarningsTaxEffect |