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Financial Instruments And Concentration Of Credit Risk (Details) (Accounts Receivable [Member], Customer Concentration Risk [Member]) | 12 Months Ended
--- | ---
Dec. 31, 2011 | Dec. 31, 2010
Accounts Receivable [Member] | Customer Concentration Risk [Member] |  |
Concentration Risk [Line Items] |  |
Gross accounts receivable (%) | 21.00% | 18.00%

X
- Definition Percentage of sales to customers on accounts receivable + References No definition available. + Details
Name: | bhe_PercentageOfSalesToCustomersOnAccountsReceivable
Namespace Prefix: | bhe_
Data Type: | num:percentItemType
Balance Type: | na
Period Type: | duration

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