Cash and Cash Equivalents - Additional Information (Details) - USD ($)	Mar. 31, 2022	Dec. 31, 2021
Cash And Cash Equivalents [Abstract]
Required Minimum Average Cash Reserve Maintained with Federal Reserve Bank	$ 0	$ 0

The required minimum average cash reserve maintained with the Federal Reserve Bank based on the amount of deposits held with the Federal Reserve Bank.

No definition available.

Name:	boh_RequiredMinimumAverageCashReserveMaintainedWithFederalReserveBank
Namespace Prefix:	boh_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	instant