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Industry Segments Data (Reconciliation of reportable segment adjusted EBITDA) (Details) (USD $)
In Thousands, unless otherwise specified |
3 Months Ended | 12 Months Ended | |||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
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Dec. 31, 2014
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Sep. 30, 2014
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Jun. 30, 2014
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Mar. 31, 2014
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Dec. 31, 2013
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Sep. 30, 2013
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Jun. 30, 2013
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Mar. 31, 2013
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Dec. 31, 2014
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Dec. 31, 2013
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Dec. 31, 2012
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| Segment Reconciliation [Abstract] | |||||||||||
| Reportable segment Adjusted EBITDA | $ 323,116gncma_AdjustedEbitda | $ 267,283gncma_AdjustedEbitda | $ 226,809gncma_AdjustedEbitda | ||||||||
| Less depreciation and amortization expense | (170,285)us-gaap_DepreciationDepletionAndAmortization | (147,259)us-gaap_DepreciationDepletionAndAmortization | (130,452)us-gaap_DepreciationDepletionAndAmortization | ||||||||
| Less share-based compensation expense | (8,392)us-gaap_ShareBasedCompensation | (6,638)us-gaap_ShareBasedCompensation | (5,040)us-gaap_ShareBasedCompensation | ||||||||
| Less non-cash contribution expense | 0us-gaap_NoncashContributionExpense | 0us-gaap_NoncashContributionExpense | (960)us-gaap_NoncashContributionExpense | ||||||||
| Less accretion expense | (1,249)us-gaap_AssetRetirementObligationAccretionExpense | (77)us-gaap_AssetRetirementObligationAccretionExpense | (508)us-gaap_AssetRetirementObligationAccretionExpense | ||||||||
| Other | 372us-gaap_OtherOperatingIncomeExpenseNet | (447)us-gaap_OtherOperatingIncomeExpenseNet | (869)us-gaap_OtherOperatingIncomeExpenseNet | ||||||||
| Operating income | 25,547us-gaap_OperatingIncomeLoss | 49,336us-gaap_OperatingIncomeLoss | 38,414us-gaap_OperatingIncomeLoss | 30,265us-gaap_OperatingIncomeLoss | 25,423us-gaap_OperatingIncomeLoss | 38,684us-gaap_OperatingIncomeLoss | 25,695us-gaap_OperatingIncomeLoss | 23,060us-gaap_OperatingIncomeLoss | 143,562us-gaap_OperatingIncomeLoss | 112,862us-gaap_OperatingIncomeLoss | 88,980us-gaap_OperatingIncomeLoss |
| Less other expense, net | (74,289)us-gaap_NonoperatingIncomeExpense | (70,178)us-gaap_NonoperatingIncomeExpense | (67,730)us-gaap_NonoperatingIncomeExpense | ||||||||
| Income before income tax expense | $ 69,273us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments | $ 42,684us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments | $ 21,250us-gaap_IncomeLossFromContinuingOperationsBeforeIncomeTaxesMinorityInterestAndIncomeLossFromEquityMethodInvestments | ||||||||
| X | ||||||||||
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- Definition
This element represents Company's specificly defined non-GAAP measure - the income or loss from continuing operations attributable to the economic entity which may also be defined as revenue less expenses from ongoing operations, after income or loss from equity method investments, but before income taxes, extraordinary items, accretion expense, non-cash contribution expense and noncontrolling interest. No definition available.
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| X | ||||||||||
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- Definition
Amount of accretion expense recognized during the period that is associated with an asset retirement obligation. Accretion expense measures and incorporates changes due to the passage of time into the carrying amount of the liability. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The aggregate expense recognized in the current period that allocates the cost of tangible assets, intangible assets, or depleting assets to periods that benefit from use of the assets. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Sum of operating profit and nonoperating income or expense before Income or Loss from equity method investments, income taxes, extraordinary items, and noncontrolling interest. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
Noncash charitable contributions made by the entity during the period. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The aggregate amount of income or expense from ancillary business-related activities (that is to say, excluding major activities considered part of the normal operations of the business). Reference 1: http://www.xbrl.org/2003/role/presentationRef
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| X | ||||||||||
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- Definition
The net result for the period of deducting operating expenses from operating revenues. No definition available.
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| X | ||||||||||
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- Definition
The net amount of other operating income and expenses, the components of which are not separately disclosed on the income statement, from items that are associated with the entity's normal revenue producing operations. No definition available.
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| X | ||||||||||
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- Details
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| X | ||||||||||
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- Definition
The aggregate amount of noncash, equity-based employee remuneration. This may include the value of stock or unit options, amortization of restricted stock or units, and adjustment for officers' compensation. As noncash, this element is an add back when calculating net cash generated by operating activities using the indirect method. Reference 1: http://www.xbrl.org/2003/role/presentationRef
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