Note 5 - Loans (Details) (USD $)	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Note 5 - Loans (Details) [Line Items]
Unamortized Loan Commitment and Origination Fees and Unamortized Discounts or Premiums	$ 998,000	$ 53,000
Age Of Appraisals That Will Considered As Stale	1 year
Additional Interest Income	649,000boch_AdditionalInterestIncome	722,000boch_AdditionalInterestIncome	759,000boch_AdditionalInterestIncome
Impaired Financing Receivable, Recorded Investment	31,408,000	42,141,000
Percentage Of Collateral Coverage To Loan Balance To Consider Restructured Loan To Performing And Accrual Status	100.00%
Obligations To Lend Additional Funds On Restructured Loans	0	0
Financing Receivable, Modifications, Recorded Investment	23,500,000	33,400,000
Financing Receivable, Modifications, Number of Contracts	7	24	30
Troubled Debt Restructurings Percentage Of Gross Portfolio Loans	3.55%	5.59%
Doubtful Grade Remaining Outstanding Period Minimum	6 months
Loans and Leases Receivable, Allowance	10,820,000	14,172,000
Percentage Of Allowance For Loan And Lease Losses Out Of Net Loans	1.64%	2.37%
Fair Value Disclosure, Off-balance Sheet Risks, Amount, Asset	206,000,000
Reserve For Unfunded Commitments Included In Other Liabilities	696,000	696,000
Percentage Of Loan Portfolio Secured By Real Estate	72.00%
Percentage Of Unallocated Allowance Amount Out Of Allowance For Loan And Lease Losses	3.00%	13.00%
Maximum Loan To Value Percentage	80.00%boch_MaximumLoanToValuePercentage
Loans 30 Days Past Due [Member]
Note 5 - Loans (Details) [Line Items]
Number Of Days For Loan Past Due	30 days
Loans 60 Days Past Due [Member]
Note 5 - Loans (Details) [Line Items]
Number Of Days For Loan Past Due	60 days
Loans 90 Days Past Due [Member]
Note 5 - Loans (Details) [Line Items]
Number Of Days For Loan Past Due	90 days
Performing Loans [Member]
Note 5 - Loans (Details) [Line Items]
Impaired Financing Receivable, Recorded Investment	$ 9,200,000	$ 8,800,000
Financing Receivable, Modifications, Number of Contracts	97
Troubled Debt Restructuring [Member]
Note 5 - Loans (Details) [Line Items]
Financing Receivable, Modifications, Number of Contracts	118
Minimum [Member]
Note 5 - Loans (Details) [Line Items]
Frequency Of External Appraisals Updating	6 months
Maximum [Member]
Note 5 - Loans (Details) [Line Items]
Frequency Of External Appraisals Updating	12 months

Additional interest income.

No definition available.

Name:	boch_AdditionalInterestIncome
Namespace Prefix:	boch_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration

- Definition

Age of appraisals that will considered as stale.

+ References

No definition available.

+ Details

Name:	boch_AgeOfAppraisalsThatWillConsideredAsStale
Namespace Prefix:	boch_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Doubtful grade remaining outstanding period minimum.

+ References

No definition available.

+ Details

Name:	boch_DoubtfulGradeRemainingOutstandingPeriodMinimum
Namespace Prefix:	boch_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

The frequencies of which external appraisals are updated.

+ References

No definition available.

+ Details

Name:	boch_FrequencyOfExternalAppraisalsUpdating
Namespace Prefix:	boch_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Maximum loan to value percentage.

+ References

No definition available.

+ Details

Name:	boch_MaximumLoanToValuePercentage
Namespace Prefix:	boch_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	boch_Note5LoansDetailsLineItems
Namespace Prefix:	boch_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Number of days for loan past due.

+ References

No definition available.

+ Details

Name:	boch_NumberOfDaysForLoanPastDue
Namespace Prefix:	boch_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Definition

Obligations to lend additional funds on restructured loans.

+ References

No definition available.

+ Details

Name:	boch_ObligationsToLendAdditionalFundsOnRestructuredLoans
Namespace Prefix:	boch_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Percentage of allowance for loan and lease losses out of net loans.

+ References

No definition available.

+ Details

Name:	boch_PercentageOfAllowanceForLoanAndLeaseLossesOutOfNetLoans
Namespace Prefix:	boch_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of collateral coverage to loan balance, to consider restructured loan to performing and accrual status.

+ References

No definition available.

+ Details

Name:	boch_PercentageOfCollateralCoverageToLoanBalanceToConsiderRestructuredLoanToPerformingAndAccrualStatus
Namespace Prefix:	boch_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Percentage of loan portfolio secured by real estate.

+ References

No definition available.

+ Details

Name:	boch_PercentageOfLoanPortfolioSecuredByRealEstate
Namespace Prefix:	boch_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

Percentage of unallocated allowance amount out of allowance for loan and lease losses.

+ References

No definition available.

+ Details

Name:	boch_PercentageOfUnallocatedAllowanceAmountOutOfAllowanceForLoanAndLeaseLosses
Namespace Prefix:	boch_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Reserve for unfunded commitments included in other liabilities.

+ References

No definition available.

+ Details

Name:	boch_ReserveForUnfundedCommitmentsIncludedInOtherLiabilities
Namespace Prefix:	boch_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Troubled debt restructurings percentage of gross portfolio loans.

+ References

No definition available.

+ Details

Name:	boch_TroubledDebtRestructuringsPercentageOfGrossPortfolioLoans
Namespace Prefix:	boch_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	instant

- Definition

The fair value of financial assets, which are not recognized in the financial statements (off-balance sheet) because they fail to meet some other criterion for recognition.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 825

-SubTopic 10

-Section 50

-Paragraph 10

-Subparagraph (a)

-URI http://asc.fasb.org/extlink&oid=35750535&loc=d3e13433-108611

+ Details

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

- Definition

Number of financing receivables that have been modified by troubled debt restructurings.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 33

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953676-111524

+ Details

Name:	us-gaap_FinancingReceivableModificationsNumberOfContracts2
Namespace Prefix:	us-gaap_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

The amount of the outstanding recorded investment related to financing receivables that have been modified by troubled debt restructurings.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 40

-Section 50

-Paragraph 4

-URI http://asc.fasb.org/extlink&oid=25495931&loc=d3e18845-111554

+ Details

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

- Definition

Amount of investment of impaired financing receivables with related allowance for credit losses and without a related allowance for credit losses.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 14A

-Subparagraph (b)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953550-111524

+ Details

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

- Definition

Amount of allowance to cover probable credit losses on loans and leases. Includes carryover of or adjustments to the allowance for loan losses in connection with business combinations. Excludes allowance for loans and leases covered under loss sharing agreements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 942

-SubTopic 210

-Section S99

-Paragraph 1

-Subparagraph (SX 210.9-03.7(d))

-URI http://asc.fasb.org/extlink&oid=6876686&loc=d3e534808-122878

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

-Publisher SEC

-Name Regulation S-X (SX)

-Number 210

-Section 03

-Paragraph 7

-Subparagraph d

-Article 9

Reference 3: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (g)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524

Reference 4: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 11B

-Subparagraph (c)(1)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=SL6953423-111524

Reference 5: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 30

-Section 50

-Paragraph 2

-Subparagraph (b)(1)(ii)

-URI http://asc.fasb.org/extlink&oid=6379141&loc=d3e15032-111544

Reference 6: http://www.xbrl.org/2003/role/presentationRef

-Publisher SEC

-Name Staff Accounting Bulletin (SAB)

-Number Topic 6

-Section L

-Subsection 1

+ Details

Name:	us-gaap_LoansAndLeasesReceivableAllowance
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Amount of deferred fees paid by borrowers and unamortized costs incurred to originate loans and leases, unamortized loan commitments and loan syndication fees, and premiums over or discounts from face amounts of loans that are being amortized into income as an adjustment to yield. Excludes amounts for loans and leases covered under loss sharing agreements.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 20

-Section 45

-Paragraph 1

-URI http://asc.fasb.org/extlink&oid=6378536&loc=d3e10092-111533

+ Details

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

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=boch_Loans30DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=boch_Loans60DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=boch_Loans90DaysPastDueMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=boch_PerformingLoansMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_FinancingReceivableRecordedInvestmentByClassOfFinancingReceivableAxis=boch_TroubledDebtRestructuringMember
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_RangeAxis=us-gaap_MinimumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type: