Note 21 - Regulatory Capital (Details Textual)	12 Months Ended
Dec. 31, 2016
Common Equity Tier One Risk Based Capital Required for Capital Adequacy to Risk Weighted Assets	4.50%
Advances from Subsidiaries Limited to as Percentage of Bank Tier One and Two Capital	10.00%

The minimum Common Equity Tier One Capital Ratio (Tier one capital divided by risk-weighted assets) required for capital adequacy purposes under the regulatory framework for prompt corrective action.

No definition available.

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