Bank of Hawaii Corporation Financial Statements - Schedule of Condensed Statements of Income (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Condensed Financial Statements Captions [Line Items]
Investment Securities Gains (Losses), Net	$ 9,932	$ (3,986)	$ (3,938)
Noninterest Expense
Total Noninterest Expense	373,807	379,227	371,624
Income Before Income Tax Benefit and Equity in Undistributed Income of Subsidiaries	189,124	285,826	270,226
Income Tax Benefit (Expense)	35,320	59,913	50,624
Net Income	153,804	225,913	219,602
Comprehensive Income	192,738	245,844	210,751
Parent Company
Condensed Financial Statements Captions [Line Items]
Dividends from Bank of Hawaii	134,000	220,000	185,000
Investment Securities Gains (Losses), Net	13,336	(850)	(819)
Other Income	154	261	198
Total Income	147,490	219,411	184,379
Noninterest Expense
Intercompany Salaries and Services	758	768	734
Other Expenses	1,864	1,682	1,701
Total Noninterest Expense	2,622	2,450	2,435
Income Before Income Tax Benefit and Equity in Undistributed Income of Subsidiaries	144,868	216,961	181,944
Income Tax Benefit (Expense)	2,395	(1,818)	(2,229)
Equity in Undistributed Income of Subsidiaries	11,331	7,134	35,429
Net Income	153,804	225,913	219,602
Comprehensive Income	$ 192,738	$ 245,844	$ 210,751