Loans - Additional Informations (Detail) (Minimum)	3 Months Ended
Mar. 31, 2015
Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Number of days past due for a loan to remain on accrual status	90 days

The number of days past the scheduled payment date that contractual amounts due on a loan have not been repaid.

No definition available.

Name:	bayk_NumberOfDaysLoansArePastDue
Namespace Prefix:	bayk_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration