Bank segment (HEI only) - Statements of Income Data (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2017	Sep. 30, 2017	Jun. 30, 2017	Mar. 31, 2017	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Interest expense
Interest on deposit liabilities									$ 13,991	$ 9,660	$ 7,167
Total interest expense									104,216	91,128	88,558
Noninterest income
Revenues									2,614,831		2,380,654
Noninterest expense
Income before income taxes									254,461	276,580	373,841
Income taxes									50,797	109,393	123,695
Net income (loss)	$ 50,046	$ 66,371	$ 46,527	$ 40,720	$ 32,843	$ 60,544	$ 39,134	$ 34,666	203,664	167,187	250,146
American Savings Bank (ASB)
Interest and dividend income
Interest and fees on loans									220,463	207,255	199,774
Interest and dividends on investment securities									37,762	28,823	19,184
Total interest and dividend income									258,225	236,078	218,958
Interest expense
Interest on deposit liabilities									13,991	9,660	7,167
Interest on other borrowings									1,548	2,496	5,588
Total interest expense									15,539	12,156	12,755
Net interest income									242,686	223,922	206,203
Provision for loan losses									14,745	10,901	16,763
Net interest income after provision for loan losses									227,941	213,021	189,440
Noninterest income
Gains on sale of investment securities, net									0	0	598
Total noninterest income									56,050	61,562	66,966
Noninterest expense
Compensation and employee benefits									98,387	94,931	89,242
Occupancy									17,073	16,699	16,321
Data processing									14,268	13,280	13,030
Services									10,847	10,994	11,054
Equipment									7,186	7,232	6,938
Office supplies, printing and postage									6,134	6,182	6,075
Marketing									3,567	3,501	3,489
FDIC insurance									2,713	2,904	3,543
Other expense									17,238	20,144	19,362
Total noninterest expense									177,413	175,867	169,054
Income before income taxes									106,578	98,716	87,352
Income taxes									24,069	31,719	30,073
Net income (loss)									82,509	66,997	57,279
American Savings Bank (ASB) | Fees from other financial services
Noninterest income
Revenues									18,937	22,796	22,384
American Savings Bank (ASB) | Fee income on deposit liabilities
Noninterest income
Revenues									21,311	22,204	21,759
American Savings Bank (ASB) | Fee income on other financial products
Noninterest income
Revenues									7,052	7,205	8,707
American Savings Bank (ASB) | Bank-owned life insurance
Noninterest income
Revenues									5,057	5,539	4,637
American Savings Bank (ASB) | Mortgage banking income
Noninterest income
Revenues									1,493	2,201	6,625
American Savings Bank (ASB) | Other income, net
Noninterest income
Revenues									$ 2,200	$ 1,617	$ 2,256