Quarterly report pursuant to Section 13 or 15(d)

Related Party Transaction (Details)

v2.4.1.9
Related Party Transaction (Details) (USD $)
3 Months Ended 1 Months Ended
Mar. 31, 2015
Mar. 31, 2014
Feb. 02, 2015
Related Party Transaction [Line Items]      
Revenue from related party $ 5,283,000us-gaap_RevenueFromRelatedParties $ 15,780,000us-gaap_RevenueFromRelatedParties  
ACS [Member]      
Related Party Transaction [Line Items]      
Payments to related party   16,200,000us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= gncma_AlaskaCommunicationsSystemsMember
6,200,000us-gaap_RelatedPartyTransactionPurchasesFromRelatedParty
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= gncma_AlaskaCommunicationsSystemsMember
Revenue from related party   $ 10,300,000us-gaap_RevenueFromRelatedParties
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= gncma_AlaskaCommunicationsSystemsMember
$ 8,100,000us-gaap_RevenueFromRelatedParties
/ us-gaap_RelatedPartyTransactionsByRelatedPartyAxis
= gncma_AlaskaCommunicationsSystemsMember