Quarterly report pursuant to Section 13 or 15(d)

Fair Value Measurements (Schedule Of Financial Assets And Liabilities Measured At Fair Value) (Details)

v2.4.1.9
Fair Value Measurements (Schedule Of Financial Assets And Liabilities Measured At Fair Value) (Details) (USD $)
Mar. 31, 2015
Dec. 31, 2014
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents $ 442,000us-gaap_CashAndCashEquivalentsFairValueDisclosure $ 1,073,000us-gaap_CashAndCashEquivalentsFairValueDisclosure
Assets (Liabilities) Net, fair value 15,905,000us-gaap_FairValueNetAssetLiability 17,216,000us-gaap_FairValueNetAssetLiability
Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 442,000us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
1,073,000us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Assets (Liabilities) Net, fair value 442,000us-gaap_FairValueNetAssetLiability
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
1,073,000us-gaap_FairValueNetAssetLiability
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Assets (Liabilities) Net, fair value 15,463,000us-gaap_FairValueNetAssetLiability
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
16,143,000us-gaap_FairValueNetAssetLiability
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Money Market Funds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 442,000us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_MoneyMarketFundsMember
1,073,000us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_MoneyMarketFundsMember
Money Market Funds [Member] | Level 1 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Cash equivalents 442,000us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_MoneyMarketFundsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
1,073,000us-gaap_CashAndCashEquivalentsFairValueDisclosure
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_MoneyMarketFundsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel1Member
Short-Term Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 4,878,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= us-gaap_ShortTermInvestmentsMember
4,603,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= us-gaap_ShortTermInvestmentsMember
Short-Term Investments [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 4,878,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= us-gaap_ShortTermInvestmentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
4,603,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= us-gaap_ShortTermInvestmentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Short-Term Investments [Member] | Certificates Of Deposit [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 1,683,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= us-gaap_ShortTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_CertificatesOfDepositMember
1,920,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= us-gaap_ShortTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_CertificatesOfDepositMember
Short-Term Investments [Member] | Certificates Of Deposit [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 1,683,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= us-gaap_ShortTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_CertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
1,920,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= us-gaap_ShortTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_CertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Short-Term Investments [Member] | Corporate Notes/Bonds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 3,195,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= us-gaap_ShortTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= jcs_CorporateNotesAndBondsMember
2,683,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= us-gaap_ShortTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= jcs_CorporateNotesAndBondsMember
Short-Term Investments [Member] | Corporate Notes/Bonds [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 3,195,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= us-gaap_ShortTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= jcs_CorporateNotesAndBondsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
2,683,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= us-gaap_ShortTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= jcs_CorporateNotesAndBondsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Long Term Investments [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 10,585,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= jcs_LongTermInvestmentsMember
11,540,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= jcs_LongTermInvestmentsMember
Long Term Investments [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 10,585,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= jcs_LongTermInvestmentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
11,540,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= jcs_LongTermInvestmentsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Long Term Investments [Member] | Certificates Of Deposit [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 5,016,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= jcs_LongTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_CertificatesOfDepositMember
5,463,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= jcs_LongTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_CertificatesOfDepositMember
Long Term Investments [Member] | Certificates Of Deposit [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 5,016,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= jcs_LongTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_CertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
5,463,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= jcs_LongTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= us-gaap_CertificatesOfDepositMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
Long Term Investments [Member] | Corporate Notes/Bonds [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments 5,569,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= jcs_LongTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= jcs_CorporateNotesAndBondsMember
6,077,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= jcs_LongTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= jcs_CorporateNotesAndBondsMember
Long Term Investments [Member] | Corporate Notes/Bonds [Member] | Level 2 [Member]    
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]    
Investments $ 5,569,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= jcs_LongTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= jcs_CorporateNotesAndBondsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member
$ 6,077,000us-gaap_InvestmentsFairValueDisclosure
/ jcs_AdditionalInvestmentInformationAxis
= jcs_LongTermInvestmentsMember
/ us-gaap_EligibleItemOrGroupForFairValueOptionAxis
= jcs_CorporateNotesAndBondsMember
/ us-gaap_FairValueByFairValueHierarchyLevelAxis
= us-gaap_FairValueInputsLevel2Member