Bank segment - Income statement data (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2020	Mar. 31, 2019
Noninterest income
Noninterest income	$ 618,605	$ 577,390
Noninterest expense
Income before income taxes	39,696	58,039
Income taxes	5,803	11,878
Net income	33,893	46,161
Other comprehensive income (loss), net of tax (benefits)	18,212	9,241
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	51,632	54,929
American Savings Bank (ASB)
Interest and dividend income
Interest and fees on loans	55,545	57,860
Interest and dividends on investment securities	9,430	10,628
Total interest and dividend income	64,975	68,488
Interest expense
Interest on deposit liabilities	3,587	4,252
Interest on other borrowings	313	528
Total interest expense	3,900	4,780
Net interest income	61,075	63,708
Provision for credit losses	10,401	6,870
Net interest income after provision for credit losses	50,674	56,838
Noninterest income
Total noninterest income	14,763	14,564
Noninterest expense
Compensation and employee benefits	25,777	25,512
Occupancy	5,267	4,670
Data processing	3,837	3,738
Services	2,809	2,426
Equipment	2,339	2,064
Office supplies, printing and postage	1,341	1,360
Marketing	802	990
FDIC insurance	102	626
Other expense	4,194	3,854
Total noninterest expense	46,468	45,240
Income before income taxes	18,969	26,162
Income taxes	3,208	5,323
Net income	15,761	20,839
Other comprehensive income (loss), net of tax (benefits)	19,847	6,252
Comprehensive income attributable to Hawaiian Electric Industries, Inc.	35,608	27,091
American Savings Bank (ASB) | Fees from other financial services
Noninterest income
Noninterest income	4,571	4,562
American Savings Bank (ASB) | Fee income on deposit liabilities
Noninterest income
Noninterest income	5,113	5,078
American Savings Bank (ASB) | Fee income on other financial products
Noninterest income
Noninterest income	1,872	1,593
American Savings Bank (ASB) | Bank-owned life insurance
Noninterest income
Noninterest income	794	2,259
American Savings Bank (ASB) | Mortgage banking income
Noninterest income
Noninterest income	2,000	614
American Savings Bank (ASB) | Other income, net
Noninterest income
Noninterest income	$ 413	$ 458