Income Taxes Income Taxes (Details) 2 - USD ($) $ in Millions	Mar. 31, 2017	Mar. 31, 2016
Income Taxes (Parenthetical) [Abstract]
Income Taxes Receivable From (Payable To) Related Parties Current	$ 0	$ 0

The carrying amount as of the balance sheet date of income taxes receivable from (payable to) related parties (typically the parent company) that are due within one year of the balance sheet date representing refunds of overpayments or recoveries based on agreed-upon resolutions of disputes with taxing authorities.

No definition available.

Name:	bhe_IncomeTaxesReceivableFromPayableToRelatedPartiesCurrent
Namespace Prefix:	bhe_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant