Acquisitions and Dispositions - Schedule of Assumptions Used in Valuation of FCC Broadcasting Licenses (Detail)	12 Months Ended
Dec. 31, 2017	Dec. 31, 2016
Greater Media Inc. [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Discount rate		9.00%
CBS Radio Stations Inc., Entercom Boston LLC and The Entercom Divestiture Trust [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Market revenue shares at maturity	5.30%
Operating income margins at maturity	36.00%
Discount rate	9.00%
Minimum [Member] \| Greater Media Inc. [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Revenue growth rates		0.30%
Market revenue shares at maturity		12.60%
Operating income margins at maturity		15.00%
Minimum [Member] \| CBS Radio Stations Inc., Entercom Boston LLC and The Entercom Divestiture Trust [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Revenue growth rates	(0.50%)
Maximum [Member] \| Greater Media Inc. [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Revenue growth rates		1.30%
Market revenue shares at maturity		48.00%
Operating income margins at maturity		31.30%
Maximum [Member] \| CBS Radio Stations Inc., Entercom Boston LLC and The Entercom Divestiture Trust [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Revenue growth rates	2.40%

Market revenue shares at maturity.

No definition available.

Name:	bbgi_MarketRevenueSharesAtMaturity
Namespace Prefix:	bbgi_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

Name:	us-gaap_FairValueInputsAssetsQuantitativeInformationLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueInputsDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of assumed long-term growth in revenues, used as an input to measure fair value.

+ References

+ Details

Name:	us-gaap_FairValueInputsLongTermRevenueGrowthRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Long-term pre-tax operating income as a percentage of net sales, used as an input to measure fair value.

+ References

+ Details

Name:	us-gaap_FairValueInputsLongtermPreTaxOperatingMarginPercent
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_BusinessAcquisitionAxis=bbgi_GreaterMediaIncMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_BusinessAcquisitionAxis=bbgi_CbsRadioStationsIncEntercomBostonLlcAndTheEntercomDivestitureTrustMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: