Bank segment (HEI only) - Key Assumptions Used in Estimating the Fair Value of ASB's Mortgage Servicing Rights (Details) - Allowance for mortgage-servicing assets – bank $ in Thousands	12 Months Ended
	Dec. 31, 2023 USD ($)	Dec. 31, 2022 USD ($)
Prepayment rate:
25 basis points adverse rate change	$ (90)	$ (92)
50 basis points adverse rate change	(204)	(214)
Discount rate:
25 basis points adverse rate change	(203)	(182)
50 basis points adverse rate change	(402)	(361)
American Savings Bank (ASB)
Mortgage Servicing Rights
Unpaid principal balance	$ 1,402,736	$ 1,451,322
Weighted average note rate	3.47%	3.38%
American Savings Bank (ASB) | Weighted average discount rate
Mortgage Servicing Rights
Weighted average measurement input	0.1000	0.1000
American Savings Bank (ASB) | Weighted average prepayment speed
Mortgage Servicing Rights
Weighted average measurement input	0.0571	0.0656