Bank segment (HEI only) - Statements of Income Data (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2016	Sep. 30, 2016	Jun. 30, 2016	Mar. 31, 2016	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Interest expense
Interest on deposit liabilities									$ 9,660	$ 7,167	$ 5,348
Total interest expense									91,128	88,558	88,476
Noninterest expense
Income before income taxes									276,580	373,841	254,788
Income taxes									109,393	123,695	93,021
Net income (loss)	$ 32,843	$ 60,544	$ 39,134	$ 34,666	$ 45,107	$ 127,613	$ 44,601	$ 32,825	167,187	250,146	161,767
American Savings Bank (ASB)
Interest and dividend income
Interest and fees on loans									207,255	199,774	184,782
Interest and dividends on investment securities									28,823	19,184	15,120
Total interest and dividend income									236,078	218,958	199,902
Interest expense
Interest on deposit liabilities									9,660	7,167	5,348
Interest on other borrowings									2,496	5,588	5,978
Total interest expense									12,156	12,755	11,326
Net interest income									223,922	206,203	188,576
Provision for loan losses									10,901	16,763	6,275
Net interest income after provision for loan losses									213,021	189,440	182,301
Noninterest income
Fees from other financial services									22,796	22,384	22,211
Fee income on deposit liabilities									22,204	21,759	22,368
Fee income on other financial products									7,205	8,707	8,094
Bank-owned life insurance									5,539	4,637	4,078
Mortgage banking income									2,201	6,625	6,330
Gains on sale of investment securities, net									0	598	0
Other income, net									1,617	2,256	4,750
Total noninterest income									61,562	66,966	67,831
Noninterest expense
Compensation and employee benefits									95,751	90,117	90,518
Occupancy									16,699	16,321	16,365
Data processing									13,280	13,030	12,103
Services									10,994	11,054	10,204
Equipment									7,232	6,938	6,577
Office supplies, printing and postage									6,182	6,075	5,749
Marketing									3,501	3,489	3,463
FDIC insurance									2,904	3,543	3,274
Other expense									19,324	18,487	18,067
Total noninterest expense									175,867	169,054	166,320
Income before income taxes									98,716	87,352	83,812
Income taxes									31,719	30,073	29,082
Net income (loss)									$ 66,997	$ 57,279	$ 54,730