Business and Summary of Significant Accounting Principles (Narratives) (Details) (USD $)
Share data in Thousands, unless otherwise specified |
3 Months Ended | |||
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Mar. 31, 2015
entity
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Mar. 31, 2014
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Dec. 31, 2014
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Feb. 02, 2015
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Business | ||||
Year founded | 1979 | |||
Principles of Consolidation | ||||
Number of VIEs | 4us-gaap_VariableInterestEntityNumberOfEntitiesWithUnavailabilityOfInformation | |||
Common Stock | ||||
Stock repurchased during period, value | $ 16,993,000us-gaap_StockRepurchasedAndRetiredDuringPeriodValue | $ 529,000us-gaap_StockRepurchasedAndRetiredDuringPeriodValue | ||
Accounts Receivable and Allowance for Doubtful Receivables | ||||
Period past due for write-off of trade accounts receivable | 120 days | |||
Revenue Recognition | ||||
Revenues | 231,089,000us-gaap_SalesRevenueNet | 216,283,000us-gaap_SalesRevenueNet | ||
Receivables | 198,721,000us-gaap_AccountsReceivableGrossCurrent | 212,441,000us-gaap_AccountsReceivableGrossCurrent | ||
Total High Cost Support Program [Member] | ||||
Revenue Recognition | ||||
Revenues |
17,300,000us-gaap_SalesRevenueNet / gncma_TypeOfProgramAxis = gncma_HighCostSupportProgramMember |
16,500,000us-gaap_SalesRevenueNet / gncma_TypeOfProgramAxis = gncma_HighCostSupportProgramMember |
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Receivables |
47,100,000us-gaap_AccountsReceivableGrossCurrent / gncma_TypeOfProgramAxis = gncma_HighCostSupportProgramMember |
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Common Stock - Class A [Member] | ||||
Common Stock | ||||
Stock repurchased during period, shares |
1,091us-gaap_StockRepurchasedAndRetiredDuringPeriodShares / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember |
26us-gaap_StockRepurchasedAndRetiredDuringPeriodShares / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember |
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Stock repurchased during period, value |
16,878,000us-gaap_StockRepurchasedAndRetiredDuringPeriodValue / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember |
529,000us-gaap_StockRepurchasedAndRetiredDuringPeriodValue / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember |
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Stock Buyback Program [Member] | ||||
Common Stock | ||||
Authorized amount, repurchase of stock |
5,000,000us-gaap_StockRepurchaseProgramAuthorizedAmount1 / us-gaap_ShareRepurchaseProgramAxis = gncma_StockBuybackProgramMember |
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Stock repurchase program, remaining value authorized to be repurchased |
111,400,000us-gaap_StockRepurchaseProgramRemainingAuthorizedRepurchaseAmount1 / us-gaap_ShareRepurchaseProgramAxis = gncma_StockBuybackProgramMember |
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Stock Buyback Program [Member] | Common Stock - Class A [Member] | ||||
Common Stock | ||||
Stock repurchased during period, shares |
1,100us-gaap_StockRepurchasedAndRetiredDuringPeriodShares / us-gaap_ShareRepurchaseProgramAxis = gncma_StockBuybackProgramMember / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember |
0us-gaap_StockRepurchasedAndRetiredDuringPeriodShares / us-gaap_ShareRepurchaseProgramAxis = gncma_StockBuybackProgramMember / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember |
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Stock repurchased during period, value |
$ 16,100,000us-gaap_StockRepurchasedAndRetiredDuringPeriodValue / us-gaap_ShareRepurchaseProgramAxis = gncma_StockBuybackProgramMember / us-gaap_StatementClassOfStockAxis = us-gaap_CommonClassAMember |
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ACS Wireless [Member] | ||||
Principles of Consolidation | ||||
Voting interests acquired |
33.33%us-gaap_BusinessAcquisitionPercentageOfVotingInterestsAcquired / us-gaap_BusinessAcquisitionAxis = gncma_ACSWirelessMember |
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Interests acquired from noncontrolling interest |
66.67%gncma_BusinessAcquisitionPercentageofVotingInterestsAcquiredfromNoncontrollingInterest / us-gaap_BusinessAcquisitionAxis = gncma_ACSWirelessMember |
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- Definition
Business Acquisition, Percentage of Voting Interests Acquired from Noncontrolling Interest No definition available.
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X | ||||||||||
- Definition
Amounts due from customers or clients, within one year of the balance sheet date (or the normal operating cycle, whichever is longer) for goods or services (including trade receivables) that have been delivered or sold in the normal course of business. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Percentage of voting equity interests acquired at the acquisition date in the business combination. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Number of shares that have been repurchased and retired during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Equity impact of the value of stock that has been repurchased and retired during the period. The excess of the purchase price over par value can be charged against retained earnings (once the excess is fully allocated to additional paid in capital). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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X | ||||||||||
- Definition
Amount of stock repurchase plan authorized. No definition available.
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- Definition
Amount remaining of a stock repurchase plan authorized. No definition available.
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X | ||||||||||
- Definition
Threshold period past due for trade accounts receivable to write off as uncollectible, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. No definition available.
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X | ||||||||||
- Definition
Number of Variable Interest Entities (VIE) or potential VIEs for which the necessary information is unable to be obtained to: (1) determine whether the legal entity is a VIE, (2) determine whether it (the reporting entity) is the VIE's primary beneficiary, or (3) perform the accounting required to consolidate the VIE for which it is determined that it (the reporting entity) is the primary beneficiary. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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- Definition
Year the entity was founded, in CCYY format. No definition available.
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