| **Intangible Assets and Goodwill (Tables)**                                                | 3 Months Ended                                                                                                                                     |
|--------------------------------------------------------------------------------------------|----------------------------------------------------------------------------------------------------------------------------------------------------|
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| **Intangible Assets [Abstract]**                                                           |                                                                                                                                               |
| Schedule Of Amortization Expense [Table Text Block]                                        |    Three Months Ended March 31,   20132012 Amortization expense$ 1,456 1,300                                    |
| Schedule of Finite-Lived Intangible Assets, Future Amortization Expense [Table Text Block] |  Years Ending December 31,   2013$ 5,392 2014  4,557 2015  3,229 2016  1,630 2017  734 |

| X                                                                                                                                                                                                                                                                              |
|--------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Tabular disclosure of amortization expense.
+ References
No definition available.
+ Details**Name:**gncma_ScheduleOfAmortizationExpenseTableTextBlock**Namespace Prefix:**gncma_**Data Type:**nonnum:textBlockItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                 |
|-----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Details**Name:**us-gaap_GoodwillAndIntangibleAssetsDisclosureAbstract**Namespace Prefix:**us-gaap_**Data Type:**xbrli:stringItemType**Balance Type:**na**Period Type:**duration |
| X                                                                                                                                                                                                                                                                                                                                                                                                                       |
|-------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|
| - Definition
Tabular disclosure of the amount of amortization expense expected to be recorded in succeeding fiscal years for finite-lived intangible assets.
+ References
No definition available.
+ Details**Name:**us-gaap_ScheduleofFiniteLivedIntangibleAssetsFutureAmortizationExpenseTableTextBlock**Namespace Prefix:**us-gaap_**Data Type:**nonnum:textBlockItemType**Balance Type:**na**Period Type:**duration |