Bank segment (HEI only) - Statements of Income Data (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2023	Dec. 31, 2022	Dec. 31, 2021
Interest expense
Interest on deposit liabilities	$ 48,905	$ 7,327	$ 4,981
Total interest expense	208,329	116,703	99,403
Noninterest income
Noninterest income	3,297,286	3,465,215
Noninterest expense
Income before income taxes	245,701	304,195	310,863
Income taxes	44,573	61,167	62,807
Net income	201,128	243,028	248,056
Other comprehensive income (loss), net of taxes	46,678	(283,495)	(51,269)
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	245,916	(42,357)	194,897
American Savings Bank (ASB)
Interest and dividend income
Interest and fees on loans	276,688	207,830	198,802
Interest and dividends on investment securities	58,095	58,044	43,464
Total interest and dividend income	334,783	265,874	242,266
Interest expense
Interest on deposit liabilities	48,905	7,327	4,981
Interest on other borrowings	33,892	5,974	59
Total interest expense	82,797	13,301	5,040
Net interest income	251,986	252,573	237,226
Provision for credit losses	10,357	2,037	(25,825)
Net interest income after provision for credit losses	241,629	250,536	263,051
Noninterest income
Gain on sale of real estate	495	1,778	0
Gain (loss) on sale of investment securities, net	(14,965)	0	528
Total noninterest income	45,410	56,972	64,660
Noninterest expense
Compensation and employee benefits	118,297	113,839	113,970
Occupancy	21,703	24,026	20,584
Data processing	20,545	17,681	17,634
Services	13,943	10,679	10,327
Equipment	11,842	10,100	9,510
Office supplies, printing and postage	4,315	4,398	4,239
Marketing	4,001	3,968	3,870
FDIC insurance	6,230	3,591	3,235
Other expense	22,762	16,985	13,783
Total noninterest expense	223,638	205,267	197,152
Income before income taxes	63,401	102,241	130,559
Income taxes	10,039	22,252	29,325
Net income	53,362	79,989	101,234
Other comprehensive income (loss), net of taxes	44,343	(298,833)	(52,728)
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	97,705	(218,844)	48,506
American Savings Bank (ASB) | Fees from other financial services
Noninterest income
Noninterest income	19,034	19,830	21,225
American Savings Bank (ASB) | Fee income on deposit liabilities
Noninterest income
Noninterest income	19,131	18,762	16,663
American Savings Bank (ASB) | Fee income on other financial products
Noninterest income
Noninterest income	10,616	10,291	8,770
American Savings Bank (ASB) | Bank-owned life insurance
Noninterest income
Noninterest income	7,390	2,533	7,318
American Savings Bank (ASB) | Mortgage banking income
Noninterest income
Noninterest income	910	1,692	9,305
American Savings Bank (ASB) | Other income, net
Noninterest income
Noninterest income	$ 2,799	$ 2,086	$ 851