Bank segment (HEI only) - Mortgage Servicing Rights and Valuation Allowance Roll Forward (Details) - American Savings Bank (ASB) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Mortgage Servicing Rights [Roll Forward]
Beginning balance	$ 8,639
Ending balance	8,062	$ 8,639
Allowance for mortgage-servicing assets – bank
Mortgage Servicing Rights [Roll Forward]
Beginning balance	8,639	9,373	$ 8,884
Amount capitalized	1,045	1,239	2,740
Amortization	(1,622)	(1,973)	(2,251)
Sale of mortgage servicing rights	0	0	0
Other-than-temporary impairment	0	0	0
Ending balance	8,062	8,639	9,373
Valuation Allowance [Roll Forward]
Valuation allowance, beginning balance	0	0	0
Provision (recovery)	0	0	0
Other-than-temporary impairment	0	0	0
Valuation allowance, ending balance	0	0	0
Net carrying amount	8,062	$ 8,639	$ 9,373
Estimated Aggregate Amortization Expenses of Mortgage Servicing Rights [Abstract]
2019	1,100
2020	1,000
2021	900
2022	800
2023	$ 700
Measurement Band A
Estimated Aggregate Amortization Expenses of Mortgage Servicing Rights [Abstract]
Risks inherent in servicing assets and servicing liabilities band percent for risk categorization	0.50%
Measurement Band B
Estimated Aggregate Amortization Expenses of Mortgage Servicing Rights [Abstract]
Risks inherent in servicing assets and servicing liabilities band percent for risk categorization	1.00%