v2.4.0.8

Acquired Intangible Asset Net - Additional Information (Detail) (USD $) In Thousands, unless otherwise specified	Oct. 31, 2014	Apr. 30, 2014
Acquired Intangible Assets Amortization [Line Items]
Acquired intangible assets	$ 12,443	$ 13,388
Discontinued Operations
Acquired Intangible Assets Amortization [Line Items]
Acquired intangible assets	$ 0	$ 32,813

X

- Details

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Namespace Prefix:	bv_
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X

- Definition

Sum of the carrying amounts of all intangible assets, excluding goodwill, as of the balance sheet date, net of accumulated amortization and impairment charges.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6388964&loc=d3e16212-109274



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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 350

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph ((a)(1),(b))

-URI http://asc.fasb.org/extlink&oid=26713463&loc=d3e16323-109275

+ Details

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Namespace Prefix:	us-gaap_
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Balance Type:	debit
Period Type:	instant