v3.5.0.1

Operating Segment and Geographic Information - Revenue from Continuing Operations by Geographic Region (Details) - USD ($) $ in Thousands | 3 Months Ended | 12 Months Ended
--- | --- | ---
Apr. 30, 2016 | [1] | Jan. 31, 2016 | Oct. 31, 2015 | Jul. 31, 2015 | Apr. 30, 2015 | Jan. 31, 2015 | Oct. 31, 2014 | Jul. 31, 2014 | Apr. 30, 2016 | Apr. 30, 2015 | Apr. 30, 2014
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue | $ 50,709 | $ 50,255 | $ 49,926 | $ 48,876 | $ 48,317 | $ 49,562 | $ 47,325 | $ 45,977 | $ 199,766 | $ 191,181 | $ 168,145
Americas [Member] |  |  |  |  |  |  |  |  |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 150,758 | 146,086 | 127,766
EMEA [Member] |  |  |  |  |  |  |  |  |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | 42,620 | 38,101 | 33,499
Other Geographic Area [Member] |  |  |  |  |  |  |  |  |  |  |
Revenues from External Customers and Long-Lived Assets [Line Items] |  |  |  |  |  |  |  |  |  |  |
Revenue |  |  |  |  |  |  |  |  | $ 6,388 | $ 6,994 | $ 6,880
[1] | During the fourth quarter of fiscal 2016, the Company recorded out of period adjustments related to errors in the timing of recognition of revenue, for which all required criteria had been satisfied in prior periods. The cumulative effect of out of period adjustments for the fourth quarter of fiscal 2016 was a $0.9 million increase in revenue. The Company has determined that these adjustments were not material to any prior annual or interim periods, and the resulting correction is not material to its annual results for fiscal 2016 or to the trend in earnings.

X
- 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_RevenuesFromExternalCustomersAndLongLivedAssetsLineItems
Namespace Prefix: | us-gaap_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration

X
- Definition Total revenue from sale of goods and services rendered during the reporting period, in the normal course of business, reduced by sales returns and allowances, and sales discounts. + References Reference 1: http://www.xbrl.org/2003/role/presentationRef -Publisher FASB -Name Accounting Standards Codification -Topic 225 -SubTopic 10 -Section S99 -Paragraph 2 -Subparagraph (SX 210.5-03.1) -URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688 + Details
Name: | us-gaap_SalesRevenueNet
Namespace Prefix: | us-gaap_
Data Type: | xbrli:monetaryItemType
Balance Type: | credit
Period Type: | duration

X
- Details
Name: | us-gaap_StatementGeographicalAxis=us-gaap_AmericasMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=us-gaap_EMEAMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |

X
- Details
Name: | us-gaap_StatementGeographicalAxis=bv_OtherGeographicAreaMember
Namespace Prefix: |
Data Type: | na
Balance Type: |
Period Type: |