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           Income Taxes (Narrative) (Details) (USD $) 
         | 
        12 Months Ended | |||
|---|---|---|---|---|
| 
           Dec. 31, 2014 
         | 
        
           Dec. 31, 2013 
         | 
        
           Dec. 31, 2012 
         | 
        
           Dec. 31, 2005 
         | 
      |
| Income Taxes [Line Items] | ||||
| Dividend payable | $ 1,446,498us-gaap_DividendsPayableCurrentAndNoncurrent | $ 1,436,318us-gaap_DividendsPayableCurrentAndNoncurrent | ||
| Uncertain tax benefit positions that would reduce the effective income tax rate if recognized | 76,000us-gaap_UnrecognizedTaxBenefitsThatWouldImpactEffectiveTaxRate | |||
| Expiration of statute of limitations | 7,000us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations | 66,000us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations | 81,000us-gaap_UnrecognizedTaxBenefitsReductionsResultingFromLapseOfApplicableStatuteOfLimitations | |
| Accrual for interest and penalties | 2,000us-gaap_UnrecognizedTaxBenefitsIncomeTaxPenaltiesAndInterestAccrued | |||
| Net increase (decrease) in accrued interest and penalties | (159,000)jcs_NetIncreaseDecreaseInAccruedInterestAndPenalties | |||
| Austin Taylor Communications, Ltd. [Member] | ||||
| Income Taxes [Line Items] | ||||
| Pretax income (losses) | 
389,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign / dei_LegalEntityAxis = jcs_AustinTaylorCommunicationsLtdMember  | 
        
428,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign / dei_LegalEntityAxis = jcs_AustinTaylorCommunicationsLtdMember  | 
        
419,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign / dei_LegalEntityAxis = jcs_AustinTaylorCommunicationsLtdMember  | 
        |
| Net operating loss carryforwards | 
6,957,000us-gaap_OperatingLossCarryforwards / dei_LegalEntityAxis = jcs_AustinTaylorCommunicationsLtdMember  | 
        |||
| Transition Networks EMEA, Ltd. [Member] | ||||
| Income Taxes [Line Items] | ||||
| Pretax income (losses) | 
(54,000)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign / dei_LegalEntityAxis = jcs_TransitionNetworksEmeaLtd.Member  | 
        
(2,754,000)us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign / dei_LegalEntityAxis = jcs_TransitionNetworksEmeaLtd.Member  | 
        
316,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign / dei_LegalEntityAxis = jcs_TransitionNetworksEmeaLtd.Member  | 
        |
| Net operating loss carryforwards | 
37,000us-gaap_OperatingLossCarryforwards / dei_LegalEntityAxis = jcs_TransitionNetworksEmeaLtd.Member  | 
        |||
| Transition Networks China [Member] | ||||
| Income Taxes [Line Items] | ||||
| Pretax income (losses) | 
345,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign / dei_LegalEntityAxis = jcs_TransitionNetworksChinaMember  | 
        
341,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign / dei_LegalEntityAxis = jcs_TransitionNetworksChinaMember  | 
        
36,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign / dei_LegalEntityAxis = jcs_TransitionNetworksChinaMember  | 
        |
| Net operating loss carryforwards | 
460,000us-gaap_OperatingLossCarryforwards / dei_LegalEntityAxis = jcs_TransitionNetworksChinaMember  | 
        |||
| Suttle Costa Rica, S.A. [Member] | ||||
| Income Taxes [Line Items] | ||||
| Pretax income (losses) | 
321,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign / dei_LegalEntityAxis = jcs_SuttleCostaRicaSMember  | 
        
152,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign / dei_LegalEntityAxis = jcs_SuttleCostaRicaSMember  | 
        
168,000us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesForeign / dei_LegalEntityAxis = jcs_SuttleCostaRicaSMember  | 
        |
| Net operating loss carryforwards | 
0us-gaap_OperatingLossCarryforwards / dei_LegalEntityAxis = jcs_SuttleCostaRicaSMember  | 
        |||
| Dividend payable | 
$ 3,500,000us-gaap_DividendsPayableCurrentAndNoncurrent / dei_LegalEntityAxis = jcs_SuttleCostaRicaSMember  | 
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- Definition 
          Net increase (decrease) in accrued interest and penalties No definition available. 
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- Definition 
          Carrying value as of the balance sheet date of dividends declared but unpaid on equity securities issued by the entity and outstanding. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          The portion of earnings or loss from continuing operations before income taxes that is attributable to foreign operations, which is defined as Income or Loss generated from operations located outside the entity's country of domicile. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Amount of operating loss carryforward, before tax effects, available to reduce future taxable income under enacted tax laws. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Amount accrued for interest on an underpayment of income taxes and penalties related to a tax position claimed or expected to be claimed in the tax return. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          Amount of decrease in unrecognized tax benefits resulting from lapses of applicable statutes of limitations. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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- Definition 
          The total amount of unrecognized tax benefits that, if recognized, would affect the effective tax rate. Reference 1: http://www.xbrl.org/2003/role/presentationRef 
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