Electric utility segment - Condensed consolidating statement of changes in common stock equity (Details) - USD ($) $ in Thousands	3 Months Ended				6 Months Ended
	Jun. 30, 2021	Mar. 31, 2021	Jun. 30, 2020	Mar. 31, 2020	Jun. 30, 2021	Jun. 30, 2020
Increase (decrease) in stockholders' equity
Beginning balance	$ 2,321,293	$ 2,337,502	$ 2,276,505	$ 2,280,260	$ 2,337,502	$ 2,280,260
Net income for common stock	63,872	64,358	48,887	33,420	128,230	82,307
Other comprehensive income, net of taxes	16,472	(44,016)	(332)	18,212	(27,544)	17,880
Common stock dividends	(37,155)	(37,156)	(36,017)	(36,019)
Ending balance	2,367,329	2,321,293	2,291,398	2,276,505	2,367,329	2,291,398
Hawaiian Electric Consolidated
Increase (decrease) in stockholders' equity
Beginning balance	2,157,385	2,141,918	2,044,499	2,047,352	2,141,918	2,047,352
Net income for common stock	41,901	43,358	42,329	23,905	85,259	66,234
Other comprehensive income, net of taxes	35	34	25	26	69	51
Common stock dividends	(27,925)	(27,925)	(26,784)	(26,784)	(55,850)	(53,568)
Ending balance	2,171,396	2,157,385	2,060,069	2,044,499	2,171,396	2,060,069
Hawaiian Electric Consolidated | Reportable Legal Entities | Hawaiian Electric Industries, Inc.
Increase (decrease) in stockholders' equity
Beginning balance		2,141,918		2,047,352	2,141,918	2,047,352
Net income for common stock	41,901		42,329		85,259	66,234
Other comprehensive income, net of taxes	35		25		69	51
Common stock dividends					(55,850)	(53,568)
Ending balance	2,171,396		2,060,069		2,171,396	2,060,069
Hawaiian Electric Consolidated | Reportable Legal Entities | Hawaii Electric Light
Increase (decrease) in stockholders' equity
Beginning balance		317,451		298,998	317,451	298,998
Net income for common stock	5,607		7,179		12,299	13,246
Other comprehensive income, net of taxes	0		3		1	4
Common stock dividends					(7,300)	(8,160)
Ending balance	322,451		304,088		322,451	304,088
Hawaiian Electric Consolidated | Reportable Legal Entities | Maui Electric
Increase (decrease) in stockholders' equity
Beginning balance		309,363		292,870	309,363	292,870
Net income for common stock	5,137		6,597		10,955	9,334
Other comprehensive income, net of taxes	0		(3)		0	(3)
Common stock dividends					(7,550)	(7,192)
Ending balance	312,768		295,009		312,768	295,009
Hawaiian Electric Consolidated | Reportable Legal Entities | Other subsidiaries
Increase (decrease) in stockholders' equity
Beginning balance		77		101	77	101
Net income for common stock	0		0		0	0
Other comprehensive income, net of taxes	0		0		0	0
Ending balance	77		101		77	101
Hawaiian Electric Consolidated | Consolidating adjustments
Increase (decrease) in stockholders' equity
Beginning balance		$ (626,891)		$ (591,969)	(626,891)	(591,969)
Net income for common stock	(10,744)		(13,776)		(23,254)	(22,580)
Other comprehensive income, net of taxes	0		0		(1)	(1)
Common stock dividends					14,850	15,352
Ending balance	$ (635,296)		$ (599,198)		$ (635,296)	$ (599,198)