Bank segment (HEI only) - Available For Sale Investment Securities (Details) $ in Thousands	Dec. 31, 2019 USD ($) issue	Dec. 31, 2018 USD ($) issue
Available-for-sale
Total amortized cost	$ 1,229,438	$ 1,421,897
Gross unrealized gains	8,015	954
Gross unrealized losses	(4,627)	(34,318)
Available-for-sale investment securities	$ 1,232,826	$ 1,388,533
Number of issues, less than 12 months | issue	21	33
Fair value, less than 12 months	$ 156,181	$ 178,068
Gross unrealized losses, less than 12 months	$ (830)	$ (1,907)
Number of issues, more than 12 months | issue	78	164
Fair value, 12 months or longer	$ 345,657	$ 1,066,295
Gross unrealized losses, 12 months or longer	(3,797)	(32,411)
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Debt Securities, Held-to-maturity	139,451	141,875
Gross unrealized gains	4,087	1,446
Gross unrealized losses	(71)	(1,264)
Held-to-maturity investment securities	$ 143,467	$ 142,057
Number of issues, less than 12 months | issue	1	3
Fair value, less than 12 months	$ 12,986	$ 29,814
Gross unrealized losses, less than 12 months	$ (71)	$ (400)
Number of issues, more than 12 months | issue	0	2
Fair value, 12 months or longer	$ 0	$ 31,505
Gross unrealized losses, 12 months or longer	0	(864)
U.S. Treasury and federal agency obligations
Available-for-sale
Total amortized cost	117,255	156,694
Gross unrealized gains	652	62
Gross unrealized losses	(120)	(2,407)
Available-for-sale investment securities	$ 117,787	$ 154,349
Number of issues, less than 12 months | issue	2	5
Fair value, less than 12 months	$ 4,110	$ 25,882
Gross unrealized losses, less than 12 months	$ (11)	$ (208)
Number of issues, more than 12 months | issue	3	19
Fair value, 12 months or longer	$ 27,637	$ 118,405
Gross unrealized losses, 12 months or longer	(109)	(2,199)
Mortgage-backed securities — issued or guaranteed by U.S. Government agencies or sponsored agencies
Available-for-sale
Total amortized cost	1,024,892	1,192,169
Gross unrealized gains	6,000	789
Gross unrealized losses	(4,507)	(31,542)
Available-for-sale investment securities	$ 1,026,385	$ 1,161,416
Number of issues, less than 12 months | issue	19	22
Fair value, less than 12 months	$ 152,071	$ 129,011
Gross unrealized losses, less than 12 months	$ (819)	$ (1,330)
Number of issues, more than 12 months | issue	75	145
Fair value, 12 months or longer	$ 318,020	$ 947,890
Gross unrealized losses, 12 months or longer	(3,688)	(30,212)
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Debt Securities, Held-to-maturity	139,451	141,875
Gross unrealized gains	4,087	1,446
Gross unrealized losses	(71)	(1,264)
Held-to-maturity investment securities	$ 143,467	$ 142,057
Number of issues, less than 12 months | issue	1	3
Fair value, less than 12 months	$ 12,986	$ 29,814
Gross unrealized losses, less than 12 months	$ (71)	$ (400)
Number of issues, more than 12 months | issue	0	2
Fair value, 12 months or longer	$ 0	$ 31,505
Gross unrealized losses, 12 months or longer	0	(864)
Corporate bonds
Available-for-sale
Total amortized cost	58,694	49,398
Gross unrealized gains	1,363	103
Gross unrealized losses	0	(369)
Available-for-sale investment securities	$ 60,057	$ 49,132
Number of issues, less than 12 months | issue	0	6
Fair value, less than 12 months	$ 0	$ 23,175
Gross unrealized losses, less than 12 months	$ 0	$ (369)
Number of issues, more than 12 months | issue	0	0
Fair value, 12 months or longer	$ 0	$ 0
Gross unrealized losses, 12 months or longer	0	0
Mortgage revenue bonds
Available-for-sale
Total amortized cost	28,597	23,636
Gross unrealized gains	0	0
Gross unrealized losses	0	0
Available-for-sale investment securities	$ 28,597	$ 23,636
Number of issues, less than 12 months | issue	0	0
Fair value, less than 12 months	$ 0	$ 0
Gross unrealized losses, less than 12 months	$ 0	$ 0
Number of issues, more than 12 months | issue	0	0
Fair value, 12 months or longer	$ 0	$ 0
Gross unrealized losses, 12 months or longer	0	0
American Savings Bank (ASB)
Available-for-sale
Available-for-sale investment securities	1,232,826	1,388,533
Debt Securities, Held-to-maturity, Fair Value to Amortized Cost [Abstract]
Debt Securities, Held-to-maturity	139,451	141,875
Held-to-maturity investment securities	$ 143,467	$ 142,057