Bank segment (HEI only) - Statements of Income Data (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Interest expense
Interest on deposit liabilities	$ 10,654	$ 16,830	$ 13,991
Total interest expense	99,808	109,339	104,216
Noninterest income
Revenues	2,269,451	2,622,025
Noninterest expense
Income before income taxes	240,624	271,409	254,461
Income taxes	40,910	51,637	50,797
Current period other comprehensive income (loss) and reclassifications, net of taxes	18,775	30,571	(8,669)
Comprehensive income	216,599	248,453	193,105
COVID-19 related costs	5,100
Incremental compensation expense	2,500
Enhanced cleaning and sanitation costs	2,000
American Savings Bank (ASB)
Interest and dividend income
Interest and fees on loans	214,134	233,632	220,463
Interest and dividends on investment securities	30,529	32,922	37,762
Total interest and dividend income	244,663	266,554	258,225
Interest expense
Interest on deposit liabilities	10,654	16,830	13,991
Interest on other borrowings	460	1,610	1,548
Total interest expense	11,114	18,440	15,539
Net interest income	233,549	248,114	242,686
Provision for credit losses	50,811	23,480	14,745
Net interest income after provision for credit losses	182,738	224,634	227,941
Noninterest income
Gain on sale of properties	0	10,762	0
Gain on sale of investment securities, net	9,275	653	0
Total noninterest income	78,123	72,778	56,050
Noninterest expense
Compensation and employee benefits	104,443	103,009	98,387
Occupancy	21,573	21,272	17,073
Data processing	14,769	15,306	14,268
Services	11,121	10,239	10,847
Equipment	9,001	8,760	7,186
Office supplies, printing and postage	4,623	5,512	6,134
Marketing	3,435	4,490	3,567
FDIC insurance	2,342	1,204	2,713
Other expense1	20,283	15,586	17,238
Total noninterest expense	191,590	185,378	177,413
Income before income taxes	69,271	112,034	106,578
Income taxes	11,688	23,061	24,069
Net income attributable to Hawaiian Electric	57,583	88,973	82,509
Current period other comprehensive income (loss) and reclassifications, net of taxes	23,608	29,406	(7,119)
Comprehensive income	81,191	118,379	75,390
American Savings Bank (ASB) | Fees from other financial services
Noninterest income
Revenues	16,447	19,275	18,937
American Savings Bank (ASB) | Fee income on deposit liabilities
Noninterest income
Revenues	16,059	20,877	21,311
American Savings Bank (ASB) | Fee income on other financial products
Noninterest income
Revenues	6,381	6,507	7,052
American Savings Bank (ASB) | Bank-owned life insurance
Noninterest income
Revenues	6,483	7,687	5,057
American Savings Bank (ASB) | Mortgage banking income
Noninterest income
Revenues	23,734	4,943	1,493
American Savings Bank (ASB) | Other income, net
Noninterest income
Revenues	$ (256)	$ 2,074	$ 2,200