Employee Stock Ownership Plan (Details Textual) (Employee Stock Ownership Plan ESOP [Member], USD $)	12 Months Ended
Dec. 31, 2012 Age	Dec. 31, 2011
Employee Stock Ownership Plan ESOP [Member]
Employee Stock Ownership Plan (Textual) [Abstract]
Noncontributory employee stock ownership plan, service period eligibility	12 months
Noncontributory employee stock ownership plan, age eligibility	21
Allocations, as a percentage of eligible participant compensation	25.00%
Participant accounts vested after two years	30.00%
Participant accounts vested after three years	40.00%
Participant accounts vested each year, from fourth year till 100% vested	20.00%
Participant accounts, total vested	100.00%
Allocated shares	158,378
Contributions to the plan	$ 0	$ 75,000
Dividends on the company's stock held by the ESOP	$ 0	$ 0

Employee stock ownership plan ESOP allocation percentage.

No definition available.

Name:	bayk_EmployeeStockOwnershipPlanEsopAllocationPercentage
Namespace Prefix:	bayk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Employee stock ownership plan ESOP minimum age qualification.

+ References

No definition available.

+ Details

Name:	bayk_EmployeeStockOwnershipPlanEsopMinimumAgeQualification
Namespace Prefix:	bayk_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

Employee stock ownership plan (ESOP), participant accounts vested after three years, percentage.

+ References

No definition available.

+ Details

Name:	bayk_EmployeeStockOwnershipPlanEsopParticipantAccountsVestedAfterThreeYearsPercentage
Namespace Prefix:	bayk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Employee stock ownership plan (ESOP), participant accounts vested after two years percentage.

+ References

No definition available.

+ Details

Name:	bayk_EmployeeStockOwnershipPlanEsopParticipantAccountsVestedAfterTwoYearsPercentage
Namespace Prefix:	bayk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Employee stock ownership plan (ESOP), participant accounts vested each year, from fourth year till hundred percentage vested, percentage.

+ References

No definition available.

+ Details

Name:	bayk_EmployeeStockOwnershipPlanEsopParticipantAccountsVestedEachYearFromFourthYearTillHundredPercentageVestedPercentage
Namespace Prefix:	bayk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Employee stock ownership plan (ESOP), participant accounts vested, percentage.

+ References

No definition available.

+ Details

Name:	bayk_EmployeeStockOwnershipPlanEsopParticipantAccountsVestedPercentage
Namespace Prefix:	bayk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	bayk_EmployeeStockOwnershipPlanTextualAbstract
Namespace Prefix:	bayk_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

This item represents the amount of cash contributions during the period made by the entity to the Employee Stock Ownership Plan (ESOP).

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 40

-Section 50

-Paragraph 1

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=6418621&loc=d3e17540-113929

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 93-6

-Paragraph 53

-Subparagraph a

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_EmployeeStockOwnershipPlanESOPCashContributionsToESOP
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Dividends paid on stock held by an employee stock ownership plan.

+ References

+ Details

Name:	us-gaap_EmployeeStockOwnershipPlanESOPDividendsPaidToESOP
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The shares or units in an ESOP trust that have been assigned to individual participant accounts based on a known formula. IRS rules require allocations to be nondiscriminatory generally based on compensation, length of service, or a combination of both. For any particular participant such shares or units may be vested, unvested, or partially vested.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 40

-Section 50

-Paragraph 1

-Subparagraph (d)

-URI http://asc.fasb.org/extlink&oid=6418621&loc=d3e17540-113929

Reference 2: http://www.xbrl.org/2003/role/presentationRef

-Publisher AICPA

-Name Statement of Position (SOP)

-Number 93-6

-Paragraph 53

-Subparagraph d

-LegacyDoc This reference is SUPERSEDED by the Accounting Standards Codification effective for interim and annual periods ending after September 15, 2009. This reference is included to help users transition from the previous accounting hierarchy and will be removed from future versions of this taxonomy.

+ Details

Name:	us-gaap_EmployeeStockOwnershipPlanESOPNumberOfAllocatedShares
Namespace Prefix:	us-gaap_
Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	instant

- Definition

Estimated period over which an employee is required to provide service in exchange for the equity-based payment award, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 718

-SubTopic 10

-Section 50

-Paragraph 2

-Subparagraph (a)(1)

-URI http://asc.fasb.org/extlink&oid=6415400&loc=d3e5070-113901

+ Details

Name:	us-gaap_ShareBasedCompensationArrangementByShareBasedPaymentAwardAwardRequisiteServicePeriod1
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration