Common stock exchange ratio.

No definition available.

Name:	bayk_CommonStockExchangeRatio
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- Definition

Percentage of ownership by acquired company's shareholders in the combined company.

+ References

No definition available.

+ Details

Name:	bayk_OwnershipPercentageByShareholdersOfAcquiredEntity
Namespace Prefix:	bayk_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of ownership by acquiring company's shareholders in the combined company.

+ References

No definition available.

+ Details

Name:	bayk_OwnershipPercentageByShareholdersOfAcquiringEntity
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Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Value of equity interests (such as common shares, preferred shares, or partnership interest) issued or issuable to acquire the entity.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)(4)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Number of shares of equity interests issued or issuable to acquire entity.

+ References

+ Details

Name:	us-gaap_BusinessAcquisitionEquityInterestsIssuedOrIssuableNumberOfSharesIssued
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Data Type:	xbrli:sharesItemType
Balance Type:	na
Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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Period Type:	duration

- Definition

This element represents acquisition-related costs incurred to effect a business combination which costs have been expensed during the period. Such costs include finder's fees; advisory, legal, accounting, valuation, and other professional or consulting fees; general administrative costs, including the costs of maintaining an internal acquisitions department; and may include costs of registering and issuing debt and equity securities.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 10
-Section 25
-Paragraph 23
-URI http://asc.fasb.org/extlink&oid=84229725&loc=d3e1043-128460

+ Details

Name:	us-gaap_BusinessCombinationAcquisitionRelatedCosts
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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

Amount after accumulated impairment loss of an asset representing future economic benefits arising from other assets acquired in a business combination that are not individually identified and separately recognized.

+ References

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 5
-URI http://asc.fasb.org/extlink&oid=77989000&loc=SL49117168-202975

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 350
-SubTopic 20
-Section 45
-Paragraph 1
-URI http://asc.fasb.org/extlink&oid=99380562&loc=d3e13770-109266

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Details

Name:	us-gaap_BusinessAcquisitionAxis=bayk_VirginiaBancorpIncMember
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Period Type:

Business Combinations - Additional Information (Detail) $ in Thousands		3 Months Ended	12 Months Ended
	Apr. 01, 2017 USD ($) shares	Mar. 31, 2017 USD ($)	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Business Acquisition [Line Items]
Goodwill during acquisition			$ 10,374	$ 10,374
Acquisition related expenses			$ 363	1,976
Virginia BanCorp
Business Acquisition [Line Items]
Common stock exchange ratio	1.178
Business combination, number of shares exchanged \| shares	4,586,221
Business combination, value of shares exchanged	$ 42,200
Ownership percentage by shareholders of acquiring entity	51.00%
Ownership percentage by shareholders of acquired entity	49.00%
Goodwill during acquisition	$ 7,600
Acquisition related expenses		$ 174		$ 2,000