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%

Percentage of sales to customers on accounts receivable

No definition available.

Name:	bhe_PercentageOfSalesToCustomersOnAccountsReceivable
Namespace Prefix:	bhe_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration