Annual report pursuant to Section 13 and 15(d)

Industry Segments Data (Reportable segment) (Details)

v2.4.1.9
Industry Segments Data (Reportable segment) (Details) (USD $)
In Thousands, unless otherwise specified
12 Months Ended
Dec. 31, 2014
Dec. 31, 2013
Dec. 31, 2012
Segment Reporting Information [Line Items]      
Total $ 910,198us-gaap_Revenues $ 811,648us-gaap_Revenues $ 710,181us-gaap_Revenues
Cost of Goods Sold 302,704us-gaap_CostOfRevenue 280,462us-gaap_CostOfRevenue 247,501us-gaap_CostOfRevenue
Contribution 607,494us-gaap_GrossProfit 531,186us-gaap_GrossProfit 462,680us-gaap_GrossProfit
Less SG&A 293,647us-gaap_SellingGeneralAndAdministrativeExpense 271,065us-gaap_SellingGeneralAndAdministrativeExpense 243,248us-gaap_SellingGeneralAndAdministrativeExpense
Plus share-based compensation expense 8,392us-gaap_ShareBasedCompensation 6,638us-gaap_ShareBasedCompensation 5,040us-gaap_ShareBasedCompensation
Plus non-cash contribution expense 0us-gaap_NoncashContributionExpense 0us-gaap_NoncashContributionExpense 960us-gaap_NoncashContributionExpense
Plus accretion expense 1,249us-gaap_AssetRetirementObligationAccretionExpense 77us-gaap_AssetRetirementObligationAccretionExpense 508us-gaap_AssetRetirementObligationAccretionExpense
Other (372)us-gaap_OtherOperatingIncomeExpenseNet 447us-gaap_OtherOperatingIncomeExpenseNet 869us-gaap_OtherOperatingIncomeExpenseNet
Adjusted EBITDA 323,116gncma_AdjustedEbitda 267,283gncma_AdjustedEbitda 226,809gncma_AdjustedEbitda
Capital expenditures 176,109gncma_CapitalExpenditures 180,554gncma_CapitalExpenditures  
Goodwill 229,560us-gaap_Goodwill 219,041us-gaap_Goodwill 77,294us-gaap_Goodwill
Total assets 2,058,498us-gaap_Assets 2,011,807us-gaap_Assets  
Wholesale      
Segment Reporting Information [Line Items]      
Total 269,977us-gaap_Revenues
/ us-gaap_SubsegmentsAxis
= gncma_WholesaleMember
197,218us-gaap_Revenues
/ us-gaap_SubsegmentsAxis
= gncma_WholesaleMember
124,745us-gaap_Revenues
/ us-gaap_SubsegmentsAxis
= gncma_WholesaleMember
Consumer      
Segment Reporting Information [Line Items]      
Total 288,014us-gaap_Revenues
/ us-gaap_SubsegmentsAxis
= gncma_ConsumerMember
274,805us-gaap_Revenues
/ us-gaap_SubsegmentsAxis
= gncma_ConsumerMember
269,357us-gaap_Revenues
/ us-gaap_SubsegmentsAxis
= gncma_ConsumerMember
Business Services      
Segment Reporting Information [Line Items]      
Total 225,963us-gaap_Revenues
/ us-gaap_SubsegmentsAxis
= gncma_BusinessServicesMember
222,814us-gaap_Revenues
/ us-gaap_SubsegmentsAxis
= gncma_BusinessServicesMember
207,892us-gaap_Revenues
/ us-gaap_SubsegmentsAxis
= gncma_BusinessServicesMember
Managed Broadband      
Segment Reporting Information [Line Items]      
Total 126,244us-gaap_Revenues
/ us-gaap_SubsegmentsAxis
= gncma_ManagedBroadbandMember
116,811us-gaap_Revenues
/ us-gaap_SubsegmentsAxis
= gncma_ManagedBroadbandMember
108,187us-gaap_Revenues
/ us-gaap_SubsegmentsAxis
= gncma_ManagedBroadbandMember
Wireless      
Segment Reporting Information [Line Items]      
Total 269,977us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
197,218us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
124,745us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
Cost of Goods Sold 90,920us-gaap_CostOfRevenue
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
68,086us-gaap_CostOfRevenue
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
58,737us-gaap_CostOfRevenue
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
Contribution 179,057us-gaap_GrossProfit
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
129,132us-gaap_GrossProfit
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
66,008us-gaap_GrossProfit
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
Less SG&A 21,631us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
20,030us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
15,475us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
Plus share-based compensation expense 0us-gaap_ShareBasedCompensation
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
0us-gaap_ShareBasedCompensation
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
0us-gaap_ShareBasedCompensation
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
Plus non-cash contribution expense     0us-gaap_NoncashContributionExpense
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
Plus accretion expense 733us-gaap_AssetRetirementObligationAccretionExpense
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
507us-gaap_AssetRetirementObligationAccretionExpense
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
269us-gaap_AssetRetirementObligationAccretionExpense
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
Other 0us-gaap_OtherOperatingIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
0us-gaap_OtherOperatingIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
0us-gaap_OtherOperatingIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
Adjusted EBITDA 158,159gncma_AdjustedEbitda
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
109,609gncma_AdjustedEbitda
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
50,802gncma_AdjustedEbitda
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
Capital expenditures 30,243gncma_CapitalExpenditures
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
28,156gncma_CapitalExpenditures
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
 
Goodwill 164,312us-gaap_Goodwill
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
155,445us-gaap_Goodwill
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
 
Total assets 625,417us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
624,740us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
 
Wireless | Wholesale      
Segment Reporting Information [Line Items]      
Total 269,977us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_WholesaleMember
197,218us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_WholesaleMember
124,745us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_WholesaleMember
Wireless | Consumer      
Segment Reporting Information [Line Items]      
Total 0us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_ConsumerMember
0us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_ConsumerMember
0us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_ConsumerMember
Wireless | Business Services      
Segment Reporting Information [Line Items]      
Total 0us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_BusinessServicesMember
0us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_BusinessServicesMember
0us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_BusinessServicesMember
Wireless | Managed Broadband      
Segment Reporting Information [Line Items]      
Total 0us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_ManagedBroadbandMember
0us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_ManagedBroadbandMember
0us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelessSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_ManagedBroadbandMember
Wireline      
Segment Reporting Information [Line Items]      
Total 640,221us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
614,430us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
585,436us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
Cost of Goods Sold 211,784us-gaap_CostOfRevenue
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
212,376us-gaap_CostOfRevenue
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
188,764us-gaap_CostOfRevenue
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
Contribution 428,437us-gaap_GrossProfit
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
402,054us-gaap_GrossProfit
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
396,672us-gaap_GrossProfit
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
Less SG&A 272,016us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
251,035us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
227,773us-gaap_SellingGeneralAndAdministrativeExpense
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
Plus share-based compensation expense 8,392us-gaap_ShareBasedCompensation
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
6,638us-gaap_ShareBasedCompensation
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
5,040us-gaap_ShareBasedCompensation
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
Plus non-cash contribution expense     960us-gaap_NoncashContributionExpense
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
Plus accretion expense 516us-gaap_AssetRetirementObligationAccretionExpense
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
(430)us-gaap_AssetRetirementObligationAccretionExpense
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
239us-gaap_AssetRetirementObligationAccretionExpense
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
Other (372)us-gaap_OtherOperatingIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
447us-gaap_OtherOperatingIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
869us-gaap_OtherOperatingIncomeExpenseNet
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
Adjusted EBITDA 164,957gncma_AdjustedEbitda
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
157,674gncma_AdjustedEbitda
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
176,007gncma_AdjustedEbitda
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
Capital expenditures 145,866gncma_CapitalExpenditures
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
152,398gncma_CapitalExpenditures
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
 
Goodwill 65,248us-gaap_Goodwill
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
63,596us-gaap_Goodwill
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
 
Total assets 1,433,081us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
1,387,067us-gaap_Assets
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
 
Wireline | Wholesale      
Segment Reporting Information [Line Items]      
Total 0us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_WholesaleMember
0us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_WholesaleMember
0us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_WholesaleMember
Wireline | Consumer      
Segment Reporting Information [Line Items]      
Total 288,014us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_ConsumerMember
274,805us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_ConsumerMember
269,357us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_ConsumerMember
Wireline | Business Services      
Segment Reporting Information [Line Items]      
Total 225,963us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_BusinessServicesMember
222,814us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_BusinessServicesMember
207,892us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_BusinessServicesMember
Wireline | Managed Broadband      
Segment Reporting Information [Line Items]      
Total $ 126,244us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_ManagedBroadbandMember
$ 116,811us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_ManagedBroadbandMember
$ 108,187us-gaap_Revenues
/ us-gaap_StatementBusinessSegmentsAxis
= gncma_WirelineSegmentMember
/ us-gaap_SubsegmentsAxis
= gncma_ManagedBroadbandMember