v3.3.1.900

Subsequent Events (Details) - Subsequent Event [Member] - USD ($) $ in Millions	1 Months Ended
	Mar. 08, 2016	Feb. 01, 2016
Subsequent Event [Line Items]
Restructuring and related cost expected percentage of positions eliminated	6.00%
Restructuring And Related Cost Expected Cost, Year One		$ 0.9
Restructuring And Related Cost Expected Cost Year Two		$ 0.6

X

- Definition

Amount expected to be recognized in earnings for the specified restructuring cost for the current fiscal year.

+ References

No definition available.

+ Details

Name:	bv_RestructuringAndRelatedCostExpectedCostYearOne
Namespace Prefix:	bv_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

Amount expected to be recognized in earnings for the specified restructuring cost in the fiscal year subsequent to the commencement of the restructuring activity.

+ References

No definition available.

+ Details

Name:	bv_RestructuringAndRelatedCostExpectedCostYearTwo
Namespace Prefix:	bv_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

X

- Definition

The expected percentage of positions to be eliminated as a result of restructuring activities.

+ References

No definition available.

+ Details

Name:	bv_Restructuringandrelatedcostexpectedpercentageofpositionseliminated
Namespace Prefix:	bv_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

X

- Definition

Detail information of subsequent event by type. User is expected to use existing line items from elsewhere in the taxonomy as the primary line items for this disclosure, which is further associated with dimension and member elements pertaining to a subsequent event.

+ References

No definition available.

+ Details

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

X

- Details

Name:	us-gaap_SubsequentEventTypeAxis=us-gaap_SubsequentEventMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: