Line of Credit Facility, Additional Borrowing Capacity

No definition available.

Name:	bbox_LineOfCreditFacilityAdditionalBorrowingCapacity
Namespace Prefix:	bbox_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

The percentage points added to the reference rate to compute the variable rate on the debt instrument.

+ References

No definition available.

+ Details

Name:	us-gaap_DebtInstrumentBasisSpreadOnVariableRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Amount borrowed under the credit facility as of the balance sheet date.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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

- Definition

Average amount borrowed under the credit facility during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityAverageOutstandingAmount
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

The effective interest rate during the reporting period.

+ 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 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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

- Details

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

- Definition

Maximum amount borrowed under the credit facility at any time during the period.

+ References

No definition available.

+ Details

Name:	us-gaap_LineOfCreditFacilityMaximumAmountOutstandingDuringPeriod
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Maximum borrowing capacity under the credit facility without consideration of any current restrictions on the amount that could be borrowed or the amounts currently outstanding under the facility.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Statement of Financial Accounting Standard (FAS)

-Number 129

-Paragraph 2, 4

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 210

-SubTopic 10

-Section S99

-Paragraph 1

-Subparagraph (SX 210.5-02.19(b),22(b))

-URI http://asc.fasb.org/extlink&oid=6877327&loc=d3e13212-122682

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 02

-Paragraph 19, 22

-Article 5

+ Details

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

- Definition

Amount of borrowing capacity currently available under the credit facility (current borrowing capacity less the amount of borrowings outstanding).

+ References

+ Details

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

Indebtedness (Revolving Credit Agreement) (Details) (USD $)	3 Months Ended		6 Months Ended
	Sep. 29, 2012	Oct. 01, 2011	Sep. 29, 2012	Oct. 01, 2011	Mar. 23, 2012
Revolving credit agreement [Member]
Revolving Credit Agreement [Line Items]
Maximum borrowing capacity					$ 400,000,000
Additional borrowing capacity with the approval of the lenders					100,000,000
Maximum amount outstanding	214,530,000	216,180,000	214,530,000	216,180,000
Weighted-average amount outstanding	206,331,000	203,889,000	198,503,000	191,726,000
Weighted-average interest rate	1.60%	1.00%	1.50%	1.10%
Unused commitments	204,906,000		204,906,000
Revolving credit agreement [Member] \| Weighted-average overnight federal fund rates [Member] \| Fixed component [Member]
Revolving Credit Agreement [Line Items]
Basis spread on variable rate					0.50%
Revolving credit agreement [Member] \| Weighted-average overnight federal fund rates [Member] \| Variable component [Member] \| Minimum [Member]
Revolving Credit Agreement [Line Items]
Basis spread on variable rate					0.00%
Revolving credit agreement [Member] \| Weighted-average overnight federal fund rates [Member] \| Variable component [Member] \| Maximum [Member]
Revolving Credit Agreement [Line Items]
Basis spread on variable rate					0.75%
Revolving credit agreement [Member] \| LIBOR [Member] \| Minimum [Member]
Revolving Credit Agreement [Line Items]
Basis spread on variable rate					0.875%
Revolving credit agreement [Member] \| LIBOR [Member] \| Maximum [Member]
Revolving Credit Agreement [Line Items]
Basis spread on variable rate					1.75%
Swing-line loans [Member]
Revolving Credit Agreement [Line Items]
Maximum borrowing capacity					25,000,000
Letters of credit [Member]
Revolving Credit Agreement [Line Items]
Maximum borrowing capacity					25,000,000
Amount outstanding	$ 4,654,000		$ 4,654,000