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Major Customers (Narrative) (Details) | 12 Months Ended
--- | ---
Dec. 31, 2013 number_of_largest_customers | Dec. 31, 2012 number_of_largest_customers | Dec. 31, 2011 number_of_largest_customers
Major Customers [Abstract] |  |  |
Sales to largest customers (Percentage) | 53.00% | 56.00% | 53.00%
Number of customers | 10 | 10 | 10

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- Details
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Namespace Prefix: | bhe_
Data Type: | xbrli:stringItemType
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- Definition Number of largest customers accounted for portion of revenue + References No definition available. + Details
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Namespace Prefix: | bhe_
Data Type: | xbrli:integerItemType
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- Definition Percentage of revenue accounted by major customers + References No definition available. + Details
Name: | bhe_PercentageOfRevenueAccountedByMajorCustomers
Namespace Prefix: | bhe_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration