Annual report pursuant to Section 13 and 15(d)

Related Party Transactions (Narrative) (Details)

v2.4.1.9
Related Party Transactions (Narrative) (Details) (USD $)
12 Months Ended 0 Months Ended 12 Months Ended 6 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Jan. 01, 2001
Dec. 31, 2001
Dec. 31, 2013
Dec. 31, 1991
Related Party Transaction [Line Items]              
Capital lease obligations $ 98,600,000us-gaap_CapitalLeaseObligations            
Amount received from related party 59,542,000us-gaap_RevenueFromRelatedParties 28,677,000us-gaap_RevenueFromRelatedParties 0us-gaap_RevenueFromRelatedParties        
Property              
Related Party Transaction [Line Items]              
Capital lease obligations             900,000us-gaap_CapitalLeaseObligations
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_LandBuildingsAndImprovementsMember
Capital Lease Obligation Addition              
Related Party Transaction [Line Items]              
Capital lease obligations             1,300,000us-gaap_CapitalLeaseObligations
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= us-gaap_CapitalAdditionsMember
Second Aircraft              
Related Party Transaction [Line Items]              
Termination period on lease       12 months      
Monthly lease payment       132,000gncma_CapitalLeaseMonthlyLeasePayment
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= gncma_AirTransportationEquipmentTwoMember
     
Capital lease deposit         1,500,000us-gaap_SecurityDeposit
/ us-gaap_PropertyPlantAndEquipmentByTypeAxis
= gncma_AirTransportationEquipmentTwoMember
   
Deposit termination period         6 months    
ACS              
Related Party Transaction [Line Items]              
Payments to related party 62,900,000us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= gncma_AlaskaCommunicationsSystemsMember
        25,100,000us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= gncma_AlaskaCommunicationsSystemsMember
 
Amount received from related party 50,900,000us-gaap_RevenueFromRelatedParties
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= gncma_AlaskaCommunicationsSystemsMember
        23,900,000us-gaap_RevenueFromRelatedParties
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= gncma_AlaskaCommunicationsSystemsMember
 
Receivables 27,900,000us-gaap_AccountsReceivableRelatedParties
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= gncma_AlaskaCommunicationsSystemsMember
           
Payables $ 7,400,000us-gaap_AccountsPayableRelatedPartiesCurrentAndNoncurrent
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= gncma_AlaskaCommunicationsSystemsMember