Electric utility segment - Condensed consolidating statement of changes in common stock equity (Details) - USD ($) $ in Thousands	3 Months Ended
Mar. 31, 2020	Mar. 31, 2019
Increase (decrease) in stockholders' equity
Beginning Balance	$ 2,280,260	$ 2,162,280
Net income for common stock	33,420	45,688
Other comprehensive income, net of taxes	18,212	9,241
Common stock dividends	(36,019)	(34,860)
Ending Balance	2,276,505	2,183,515
Consolidating adjustments
Increase (decrease) in stockholders' equity
Beginning Balance	(591,969)	(576,838)
Net income for common stock	(8,804)	(11,849)
Other comprehensive income, net of taxes	(1)	(1)
Common stock dividends	7,676	6,312
Common stock issuance expenses	1	2
Ending Balance	(593,097)	(582,374)
Hawaiian Electric (parent only) \| Reportable Legal Entities
Increase (decrease) in stockholders' equity
Beginning Balance	2,047,352	1,957,641
Net income for common stock	23,905	32,126
Other comprehensive income, net of taxes	26	24
Common stock dividends	(26,784)	(25,313)
Common stock issuance expenses	0	0
Ending Balance	2,044,499	1,964,478
HELCO \| Reportable Legal Entities
Increase (decrease) in stockholders' equity
Beginning Balance	298,998	295,874
Net income for common stock	6,067	5,169
Other comprehensive income, net of taxes	1	1
Common stock dividends	(4,080)	(2,545)
Common stock issuance expenses	0	(2)
Ending Balance	300,986	298,497
Maui Electric \| Reportable Legal Entities
Increase (decrease) in stockholders' equity
Beginning Balance	292,870	280,863
Net income for common stock	2,737	6,680
Other comprehensive income, net of taxes	0	0
Common stock dividends	(3,596)	(3,767)
Common stock issuance expenses	(1)	0
Ending Balance	292,010	283,776
Other subsidiaries \| Reportable Legal Entities
Increase (decrease) in stockholders' equity
Beginning Balance	101	101
Net income for common stock	0	0
Other comprehensive income, net of taxes	0	0
Common stock dividends	0	0
Common stock issuance expenses	0	0
Ending Balance	101	101
Hawaiian Electric Company, Inc. and Subsidiaries
Increase (decrease) in stockholders' equity
Beginning Balance	2,047,352	1,957,641
Net income for common stock	23,905	32,126
Other comprehensive income, net of taxes	26	24
Common stock dividends	(26,784)	(25,313)
Common stock issuance expenses	0	0
Ending Balance	$ 2,044,499	$ 1,964,478

Amount of decrease in additional paid in capital (APIC) resulting from direct costs associated with issuing stock. Includes, but is not limited to, legal and accounting fees and direct costs associated with stock issues under a shelf registration.

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