Note 5 - Loans (Details) - Impaired Loans by Loan Class (USD $) In Thousands, unless otherwise specified	Dec. 31, 2014	Dec. 31, 2013
Financing Receivable, Impaired [Line Items]
Recorded investment with no related allowance recorded	$ 21,500	$ 19,989
Unpaid principle balance with no related allowance recorded	32,353	24,820
Recorded investment with an allowance recorded	9,908	22,152
Unpaid principle balance with an allowance recorded	10,635	23,378
Related allowance	1,556	4,994
Subtotal:
Recorded investment	31,408	42,141
Unpaid principle balance	42,988	48,198
Related allowance	1,556	4,994
Commercial Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with no related allowance recorded	4,298
Unpaid principle balance with no related allowance recorded	8,461
Recorded investment with an allowance recorded	2,299	6,590
Unpaid principle balance with an allowance recorded	2,317	6,808
Related allowance	314	2,988
Subtotal:
Recorded investment	6,597	6,590
Unpaid principle balance	10,778	6,808
Related allowance	314	2,988
Commercial Real Estate Other Receivable [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with no related allowance recorded	8,287	15,736
Unpaid principle balance with no related allowance recorded	12,309	18,184
Recorded investment with an allowance recorded	3,466	6,011
Unpaid principle balance with an allowance recorded	4,064	6,020
Related allowance	432	814
Subtotal:
Related allowance	432	814
Residential One To Four Family [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with no related allowance recorded	8,714	3,714
Unpaid principle balance with no related allowance recorded	11,381	6,091
Recorded investment with an allowance recorded	3,529	8,805
Unpaid principle balance with an allowance recorded	3,640	9,804
Related allowance	506	963
Subtotal:
Related allowance	506	963
Residential Real Estate and Home Equities [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with no related allowance recorded	201	539
Unpaid principle balance with no related allowance recorded	202	545
Recorded investment with an allowance recorded	579	746
Unpaid principle balance with an allowance recorded	579	746
Related allowance	289	229
Subtotal:
Related allowance	289	229
Consumer Other Financing Receivable [Member]
Financing Receivable, Impaired [Line Items]
Recorded investment with an allowance recorded	35
Unpaid principle balance with an allowance recorded	35
Related allowance	15
Subtotal:
Recorded investment	35
Unpaid principle balance	35
Related allowance	15
Commercial Real Estate Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Related allowance	432	814
Subtotal:
Recorded investment	11,753	21,747
Unpaid principle balance	16,373	24,204
Related allowance	432	814
Residential Portfolio Segment [Member]
Financing Receivable, Impaired [Line Items]
Related allowance	795	1,192
Subtotal:
Recorded investment	13,023	13,804
Unpaid principle balance	15,802	17,186
Related allowance	$ 795	$ 1,192

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

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

- 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 for credit losses related to recorded investment.

+ References

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

-Publisher FASB

-Name Accounting Standards Codification

-Topic 310

-SubTopic 10

-Section 50

-Paragraph 15

-Subparagraph (a)(3)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524

+ Details

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

- Definition

Amount of unpaid principal balance of impaired financing receivables with related allowance for credit losses and without 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 15

-Subparagraph (a)(4)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524

+ Details

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

- Definition

Amount of investment in impaired financing receivables for which there is no related allowance for credit losses.

+ References

+ Details

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

- Definition

Amount of unpaid principal balance of impaired financing receivables for which there is no 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 15

-Subparagraph (a)(4)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524

+ Details

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

- Definition

Amount of investment in impaired financing receivables for which there is a related allowance for credit losses.

+ References

+ Details

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

- Definition

Unpaid principal balance of impaired financing receivables for which there is 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 15

-Subparagraph (a)(4)

-URI http://asc.fasb.org/extlink&oid=35738203&loc=d3e5212-111524

+ Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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

- Details

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