Note 12 - Fair Values (Details Textual) - USD ($) $ in Thousands	6 Months Ended
Jun. 30, 2017	Jun. 30, 2016	Dec. 31, 2016
Future Cash Flows Discounted	3.17%
Impairment of Real Estate, Net of Capitalized Costs	$ 52	$ 76
Carrying Value of Loans Fully Charged off	$ 0
Minimum [Member]
Other Real Estate Owned Fair Value Adjustments Estimated Selling Costs Percentage	8.00%
Maximum [Member]
Other Real Estate Owned Fair Value Adjustments Estimated Selling Costs Percentage	34.00%
Collateral Impaired Loans [Member]
Collateral Dependent Impaired Loans Carrying Amount	$ 61		$ 81
Allowance for Loan and Lease Losses, Adjustments, Other	20
Other Real Estate Owned [Member]
Allowance for Loan and Lease Losses, Adjustments, Other	$ 81
Number of Real Estate Properties	4
OREO Carrying Amount	$ 931		$ 1,100
Impairment of Real Estate, Net of Capitalized Costs	$ 52

The carrying value of loans fully charged off.

No definition available.

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Namespace Prefix:	boch_
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- Definition

The carrying amount on collateral dependent impaired loans.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

Future cash flows discounted.

+ References

No definition available.

+ Details

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Period Type:	instant

- Definition

The charge against earnings in the period to reduce the carrying amount of real property to fair value, net of capitalized costs.

+ References

No definition available.

+ Details

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Namespace Prefix:	boch_
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Balance Type:	debit
Period Type:	duration

- Definition

The carrying amount on OREO.

+ References

No definition available.

+ Details

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Namespace Prefix:	boch_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant

- Definition

Represents the percentage by which OREO fair values are adjusted for estimated selling costs.

+ References

No definition available.

+ Details

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

- Definition

Amount of other addition (reduction) in allowance reserve for credit loss.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 310
-SubTopic 10
-Section 50
-Paragraph 15
-URI http://asc.fasb.org/extlink&oid=84173941&loc=d3e5212-111524

Reference 2: 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

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Balance Type:	credit
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- Definition

The number of real estate properties owned as of the balance sheet date.

+ References

No definition available.

+ Details

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