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Defined Contribution Plan - Additional Information (Detail) - USD ($) | 12 Months Ended
--- | ---
Dec. 31, 2015 | Dec. 31, 2014
Schedule Of Sale Of Subsidiary [Abstract] |  |
Employer matching contributions | $ 0 | $ 0

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- Definition Schedule Of Sale Of Subsidiary [Abstract] + References No definition available. + Details
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Namespace Prefix: | bbgi_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

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- Definition Amount of discretionary contributions made by an employer to a defined contribution plan. + References No definition available. + Details
Name: | us-gaap_DefinedContributionPlanEmployerDiscretionaryContributionAmount
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | debit
Period Type: | duration