Bank segment - Income Statement Data (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2024	Mar. 31, 2024	Jun. 30, 2023	Mar. 31, 2023	Jun. 30, 2024	Jun. 30, 2023
Noninterest income
Noninterest income	$ 797,257		$ 790,988		$ 1,572,401	$ 1,613,372
Noninterest expense
Goodwill impairment					82,190	0
Loss before income taxes	(1,742,280)		69,367		(1,688,011)	139,671
Income tax expense (benefit)	(447,269)		14,284		(435,595)	29,394
Net income (loss)	(1,295,011)		55,083		(1,252,416)	110,277
Other comprehensive (loss) income, net of tax benefits	1,594	$ (9,801)	(7,609)	$ 20,488	(8,207)	12,879
Comprehensive income (loss) attributable to Hawaiian Electric Industries, Inc.	(1,293,890)		47,001		(1,261,569)	122,210
American Savings Bank (ASB)
Interest and dividend income
Interest and fees on loans	72,960		67,966		145,931	132,808
Interest and dividends on investment securities	13,218		13,775		28,182	28,412
Interest and dividend income	86,178		81,741		174,113	161,220
Interest expense
Interest on deposit liabilities	18,015		9,661		35,447	16,498
Interest on other borrowings	6,479		8,852		14,633	16,573
Total interest expense	24,494		18,513		50,080	33,071
Net interest income	61,684		63,228		124,033	128,149
Provision for credit losses	(1,910)		43		(4,069)	1,218
Net interest income after provision for credit losses	63,594		63,185		128,102	126,931
Noninterest income
Gain on sale of real estate	0		495		0	495
Total noninterest income	15,765		15,639		32,974	30,017
Noninterest expense
Compensation and employee benefits	29,802		29,394		62,261	59,598
Occupancy	5,220		5,539		10,283	11,127
Data processing	4,960		5,095		9,806	10,107
Services	4,250		2,689		8,401	5,284
Equipment	2,477		2,957		5,126	5,603
Office supplies, printing and postage	1,006		1,109		2,024	2,274
Marketing	747		834		1,523	1,850
Goodwill impairment	82,190		0		82,190	0
Other expense	5,813		6,152		10,755	12,343
Noninterest expense	136,465		53,769		192,369	108,186
Loss before income taxes	(57,106)		25,055		(31,293)	48,762
Income tax expense (benefit)	(11,319)		4,851		(6,440)	9,996
Net income (loss)	(45,787)		20,204		(24,853)	38,766
Other comprehensive (loss) income, net of tax benefits	1,633		(7,210)		(8,135)	11,220
Comprehensive income (loss) attributable to Hawaiian Electric Industries, Inc.	(44,154)		12,994		(32,988)	49,986
American Savings Bank (ASB) | Fees from other financial services
Noninterest income
Noninterest income	5,133		5,009		10,007	9,688
American Savings Bank (ASB) | Fee income on deposit liabilities
Noninterest income
Noninterest income	4,630		4,504		9,528	9,103
American Savings Bank (ASB) | Fee income on other financial products
Noninterest income
Noninterest income	2,960		2,768		5,703	5,512
American Savings Bank (ASB) | Bank-owned life insurance
Noninterest income
Noninterest income	2,255		1,955		5,839	3,380
American Savings Bank (ASB) | Mortgage banking income
Noninterest income
Noninterest income	364		230		788	360
American Savings Bank (ASB) | Other income, net
Noninterest income
Noninterest income	$ 423		$ 678		$ 1,109	$ 1,479