-- None. No documentation exists for this element. --

No definition available.

Name:	boh_IncomeTaxesAbstract
Namespace Prefix:	boh_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the minimum percentage of likelihood of tax position being realized upon ultimate settlement, if the tax position meets the more likely than not recognition threshold.

+ References

No definition available.

+ Details

Name:	boh_MinimumPercentageOfLikelihoodOfTaxPositionBeingRealizedUponUltimateSettlement
Namespace Prefix:	boh_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the minimum percentage of net actuarial gain (loss) to be amortized in net periodic benefit costs.

+ References

No definition available.

+ Details

Name:	boh_MinimumPercentageOfNetActurialGainLossToBeAmortizedInNetPeriodicBenefitCost
Namespace Prefix:	boh_
Data Type:	num:percentItemType
Balance Type:	na
Period Type:	duration

- Definition

Represents the number of Company's pension plans.

+ References

No definition available.

+ Details

Name:	boh_NumberOfPensionPlans
Namespace Prefix:	boh_
Data Type:	xbrli:integerItemType
Balance Type:	na
Period Type:	duration

- Definition

-- None. No documentation exists for this element. --

+ References

No definition available.

+ Details

Name:	boh_PensionAndPostretirementBenefitPlansAbstract
Namespace Prefix:	boh_
Data Type:	xbrli:stringItemType
Balance Type:	na
Period Type:	duration

- Definition

Amount charged to advertising expense for the period, which are expenses incurred with the objective of increasing revenue for a specified brand, product or product line.

+ References

Reference 1: http://www.xbrl.org/2003/role/disclosureRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 720
-SubTopic 35
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=6420018&loc=d3e36677-107848

+ Details

Name:	us-gaap_AdvertisingExpense
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- References

No definition available.

+ Details

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

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

- Definition

Useful life of long lived, physical assets used in the normal conduct of business and not intended for resale, in 'PnYnMnDTnHnMnS' format, for example, 'P1Y5M13D' represents the reported fact of one year, five months, and thirteen days. Examples include, but not limited to, land, buildings, machinery and equipment, office equipment, furniture and fixtures, and computer equipment.

+ References

No definition available.

+ Details

Name:	us-gaap_PropertyPlantAndEquipmentUsefulLife
Namespace Prefix:	us-gaap_
Data Type:	xbrli:durationItemType
Balance Type:	na
Period Type:	duration

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_BuildingMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	srt_RangeAxis=srt_MaximumMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

- Details

Name:	us-gaap_PropertyPlantAndEquipmentByTypeAxis=us-gaap_EquipmentMember
Namespace Prefix:
Data Type:	na
Balance Type:
Period Type:

Summary of Significant Accounting Policies (Property and equipment and other) (Details 2) $ in Millions	12 Months Ended
	Dec. 31, 2019 USD ($) plan	Dec. 31, 2018 USD ($)	Dec. 31, 2017 USD ($)
Pension and Postretirement Benefit Plans
Number of company's pension plans \| plan	2
Minimum percentage of net acturial gain (loss) will be amortized in net periodic benefit cost	10.00%
Income Taxes
Minimum percentage of likelihood of tax position being realized upon ultimate settlement according to management's judgment	50.00%
Advertising Costs
Advertising costs \| $	$ 6.1	$ 6.0	$ 6.0
Building \| Maximum [Member]
Premises and Equipment
Estimated useful lives (in years)	30 years
Equipment \| Maximum [Member]
Premises and Equipment
Estimated useful lives (in years)	10 years