Electric utility segment - Consolidating Statements of Changes in Common Stock Equity (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020	Dec. 31, 2019
Increase (decrease) in stockholders' equity
Beginning balance	$ 2,337,502	$ 2,280,260	$ 2,162,280
Net income for common stock	246,166	197,824	217,882
Other comprehensive income (loss), net of taxes (benefits)	(51,269)	18,775	30,571
Common stock dividends	(148,643)	(144,096)	(139,463)
Ending balance	2,390,884	2,337,502	2,280,260
Hawaiian Electric (parent only)
Increase (decrease) in stockholders' equity
Beginning balance	2,337,502
Ending balance	2,390,884	2,337,502
Eliminations And Reconciling Items
Increase (decrease) in stockholders' equity
Dissolution of subsidiary		24
Hawaiian Electric Company, Inc. and Subsidiaries
Increase (decrease) in stockholders' equity
Beginning balance	2,141,918	2,047,352	1,957,641
Net income for common stock	177,642	169,340	156,840
Other comprehensive income (loss), net of taxes (benefits)	(361)	(1,640)	(1,378)
Issuance of common stock, net of expenses	54,400	34,000	35,501
Common stock dividends	(111,700)	(107,134)	(101,252)
Dissolution of subsidiary		0
Ending balance	2,261,899	2,141,918	2,047,352
Hawaiian Electric Company, Inc. and Subsidiaries | Reportable Legal Entities | Hawaiian Electric (parent only)
Increase (decrease) in stockholders' equity
Beginning balance	2,141,918	2,047,352	1,957,641
Net income for common stock	177,642	169,340	156,840
Other comprehensive income (loss), net of taxes (benefits)	(361)	(1,640)	(1,378)
Issuance of common stock, net of expenses	54,400	34,000	35,501
Common stock dividends	(111,700)	(107,134)	(101,252)
Ending balance	2,261,899	2,141,918	2,047,352
Hawaiian Electric Company, Inc. and Subsidiaries | Reportable Legal Entities | Hawaii Electric Light
Increase (decrease) in stockholders' equity
Beginning balance	317,451	298,998	295,874
Net income for common stock	21,180	27,493	20,817
Other comprehensive income (loss), net of taxes (benefits)	66	(220)	(12)
Issuance of common stock, net of expenses	8,803	7,500	(1)
Common stock dividends	(14,600)	(16,320)	(17,680)
Ending balance	332,900	317,451	298,998
Hawaiian Electric Company, Inc. and Subsidiaries | Reportable Legal Entities | Maui Electric
Increase (decrease) in stockholders' equity
Beginning balance	309,363	292,870	280,863
Net income for common stock	24,173	20,011	22,350
Other comprehensive income (loss), net of taxes (benefits)	227	(134)	(174)
Issuance of common stock, net of expenses	24,597	11,000	4,899
Common stock dividends	(15,100)	(14,384)	(15,068)
Ending balance	343,260	309,363	292,870
Hawaiian Electric Company, Inc. and Subsidiaries | Reportable Legal Entities | Other subsidiaries
Increase (decrease) in stockholders' equity
Beginning balance	77	101	101
Dissolution of subsidiary		(24)
Ending balance	77	77	101
Hawaiian Electric Company, Inc. and Subsidiaries | Consolidating adjustments
Increase (decrease) in stockholders' equity
Beginning balance	(626,891)	(591,969)	(576,838)
Net income for common stock	(45,353)	(47,504)	(43,167)
Other comprehensive income (loss), net of taxes (benefits)	(293)	354	186
Issuance of common stock, net of expenses	(33,400)	(18,500)	(4,898)
Common stock dividends	29,700	30,704	32,748
Ending balance	$ (676,237)	$ (626,891)	$ (591,969)