DEBT - Borrowings Under Revolving Facility (Details) - Credit Agreement - Texas Capital Bank, National Association (TCB) - Revolving Credit Facility - USD ($) $ in Thousands	Jun. 26, 2016	Dec. 27, 2015
Line of Credit Facility [Line Items]
Initial borrowing amount	$ 5,815	$ 6,217
Debt instrument, interest rate, stated percentage for initial borrowing amount	4.00%	4.00%
Second borrowing amount	$ 3,000	$ 3,000
Debt instrument, interest rate, stated percentage for second borrowing amount	3.88%	3.57%
Third borrowing amount	$ 6,000	$ 4,000
Debt instrument, interest rate, stated percentage for third borrowing amount	3.70%	3.61%
Fourth borrowing amount	$ 3,000	$ 3,000
Debt instrument, interest rate, stated percentage for fourth borrowing amount	3.69%	3.77%
Total borrowing amount	$ 17,815	$ 16,217

Debt Instrument, Interest Rate, Effective Percentage for Fourth Borrowing Amount

No definition available.

Name:	bgsf_DebtInstrumentInterestRateEffectivePercentageforFourthBorrowingAmount
Namespace Prefix:	bgsf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument, Interest Rate, Effective Percentage for Initial Borrowing Amount

+ References

No definition available.

+ Details

Name:	bgsf_DebtInstrumentInterestRateEffectivePercentageforInitialBorrowingAmount
Namespace Prefix:	bgsf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument, Interest Rate, Effective Percentage for Second Borrowing Amount

+ References

No definition available.

+ Details

Name:	bgsf_DebtInstrumentInterestRateEffectivePercentageforSecondBorrowingAmount
Namespace Prefix:	bgsf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Debt Instrument, Interest Rate, Effective Percentage for Third Borrowing Amount

+ References

No definition available.

+ Details

Name:	bgsf_DebtInstrumentInterestRateEffectivePercentageforThirdBorrowingAmount
Namespace Prefix:	bgsf_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Line of Credit Facility, Fourth Borrowing Amount

+ References

No definition available.

+ Details

Name:	bgsf_LineofCreditFacilityFourthBorrowingAmount
Namespace Prefix:	bgsf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of Credit Facility, Initial Borrowing Amount

+ References

No definition available.

+ Details

Name:	bgsf_LineofCreditFacilityInitialBorrowingAmount
Namespace Prefix:	bgsf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of Credit Facility, Second Borrowing Amount

+ References

No definition available.

+ Details

Name:	bgsf_LineofCreditFacilitySecondBorrowingAmount
Namespace Prefix:	bgsf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Line of Credit Facility, Third Borrowing Amount

+ References

No definition available.

+ Details

Name:	bgsf_LineofCreditFacilityThirdBorrowingAmount
Namespace Prefix:	bgsf_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The carrying value as of the balance sheet date of the current and noncurrent portions of long-term obligations drawn from a line of credit, which is a bank's commitment to make loans up to a specific amount. Examples of items that might be included in the application of this element may consist of letters of credit, standby letters of credit, and revolving credit arrangements, under which borrowings can be made up to a maximum amount as of any point in time conditional on satisfaction of specified terms before, as of and after the date of drawdowns on the line. Includes short-term obligations that would normally be classified as current liabilities but for which (a) postbalance sheet date issuance of a long term obligation to refinance the short term obligation on a long term basis, or (b) the enterprise has entered into a financing agreement that clearly permits the enterprise to refinance the short-term obligation on a long term basis and the following conditions are met (1) the agreement does not expire within 1 year and is not cancelable by the lender except for violation of an objectively determinable provision, (2) no violation exists at the BS date, and (3) the lender has entered into the financing agreement is expected to be financially capable of honoring the agreement.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 210
-SubTopic 10
-Section S99
-Paragraph 1
-Subparagraph (SX 210.5-02(22))
-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 944
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.7-03(16))
-URI http://asc.fasb.org/extlink&oid=6879938&loc=d3e572229-122910

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 942
-SubTopic 210
-Section S99
-Paragraph 1
-Subparagraph (SX 210.9-03(16))
-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

+ Details

Name:	us-gaap_LineOfCredit
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

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

- Details

Name:	us-gaap_DebtInstrumentAxis=bgsf_CreditAgreementMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_LineOfCreditFacilityAxis=bgsf_TexasCapitalBankNationalAssociationTCBMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_CreditFacilityAxis=us-gaap_RevolvingCreditFacilityMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: