Fair Value Measurements (Information Regarding Quantitative Inputs Used To Value Assets Classified As Level 3) (Details) - Significant Unobservable Inputs (Level 3) [Member] - USD ($)	3 Months Ended	12 Months Ended
Mar. 31, 2018	Dec. 31, 2017
Impaired Loans [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value	$ 2,266,000	$ 2,523,000
Impaired Loans [Member] \| Maximum [Member] \| Discounted Appraised Value [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Selling cost	10.00%	10.00%
Discount for lack of marketability and age of appraisal	20.00%	20.00%
Impaired Loans [Member] \| Minimum [Member] \| Discounted Appraised Value [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Selling cost	0.00%	0.00%
Discount for lack of marketability and age of appraisal	0.00%	0.00%
Impaired Loans [Member] \| Weighted Average [Member] \| Discounted Appraised Value [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Selling cost	8.00%	8.00%
Discount for lack of marketability and age of appraisal	6.00%	6.00%
OREO [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Assets, Fair Value	$ 2,096,000	$ 2,650,000
OREO [Member] \| Maximum [Member] \| Discounted Appraised Value [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Selling cost	10.00%	10.00%
Discount for lack of marketability and age of appraisal	25.00%	25.00%
OREO [Member] \| Minimum [Member] \| Discounted Appraised Value [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Selling cost	0.00%	0.00%
Discount for lack of marketability and age of appraisal	0.00%	0.00%
OREO [Member] \| Weighted Average [Member] \| Discounted Appraised Value [Member]
Fair Value Inputs, Assets, Quantitative Information [Line Items]
Selling cost	6.00%	6.00%
Discount for lack of marketability and age of appraisal	15.00%	15.00%

Fair value portion of probable future economic benefits obtained or controlled by an entity as a result of past transactions or events.

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (a)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

Name:	us-gaap_AssetsFairValueDisclosure
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- 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

Name:	us-gaap_FairValueInputsAssetsQuantitativeInformationLineItems
Namespace Prefix:	us-gaap_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Adjustment to the discount rate used to measure fair value for lack of ability to convert business interests into cash quickly.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueInputsDiscountForLackOfMarketability
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Interest rate used to find the present value of an amount to be paid or received in the future as an input to measure fair value. For example, but not limited to, weighted average cost of capital (WACC), cost of capital, cost of equity and cost of debt.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 820
-SubTopic 10
-Section 50
-Paragraph 2
-Subparagraph (bbb)
-URI http://asc.fasb.org/extlink&oid=66048111&loc=d3e19207-110258

+ Details

Name:	us-gaap_FairValueInputsDiscountRate
Namespace Prefix:	us-gaap_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_FairValueByAssetClassAxis=botj_ImpairedLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByFairValueHierarchyLevelAxis=us-gaap_FairValueInputsLevel3Member
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_ValuationTechniqueAxis=botj_DiscountedAppraisedValueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_RangeAxis=us-gaap_WeightedAverageMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FairValueByAssetClassAxis=botj_OtherRealEstateOwnedMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: