Condensed Consolidated Statements of Changes in Shareholders' Equity and Common Stock Equity (unaudited) - USD ($) $ in Thousands	Total	Hawaiian Electric Company, Inc. and Subsidiaries	Common stock	Common stock Hawaiian Electric Company, Inc. and Subsidiaries	Premium on capital stock Hawaiian Electric Company, Inc. and Subsidiaries	Retained Earnings	Retained Earnings Hawaiian Electric Company, Inc. and Subsidiaries	Accumulated other comprehensive income (loss)	Accumulated other comprehensive income (loss) Hawaiian Electric Company, Inc. and Subsidiaries
Beginning Balance at Dec. 31, 2016	$ 2,066,753	$ 1,799,787	$ 1,660,910	$ 106,818	$ 601,491	$ 438,972	$ 1,091,800	$ (33,129)	$ (322)
Beginning Balance (in shares) at Dec. 31, 2016			108,583,000	16,020,000
Increase (decrease) in stockholders' equity
Net income for common stock	132,927	94,596				132,927	94,596
Other comprehensive income (loss), net of tax (benefits)	3,909	521						3,909	521
Issuance of common stock, net of expenses	582		$ 582
Issuance of common stock, net of expenses (in shares)			203,000
Common stock dividends (93¢ per share)	(101,149)	(65,825)				(101,149)	(65,825)
Common stock issuance expenses		(4)			(4)
Ending Balance at Sep. 30, 2017	2,103,022	1,829,075	$ 1,661,492	$ 106,818	601,487	470,750	1,120,571	(29,220)	199
Ending Balance (in shares) at Sep. 30, 2017			108,786,000	16,020,000
Beginning Balance at Dec. 31, 2017	$ 2,097,386	1,845,283	$ 1,662,491	$ 107,634	614,675	476,836	1,124,193	(41,941)	(1,219)
Beginning Balance (in shares) at Dec. 31, 2017	108,787,807		108,788,000	16,142,000
Increase (decrease) in stockholders' equity
Net income for common stock	$ 152,201	108,356				152,201	108,356
Other comprehensive income (loss), net of tax (benefits)	(21,187)	85						(21,187)	85
Issuance of common stock, net of expenses	4,880		$ 4,880
Issuance of common stock, net of expenses (in shares)			91,000
Common stock dividends (93¢ per share)	(101,235)	(77,479)				(101,235)	(77,479)
Common stock issuance expenses		(8)			(8)
Ending Balance at Sep. 30, 2018	$ 2,132,045	$ 1,876,237	$ 1,667,371	$ 107,634	$ 614,667	$ 527,802	$ 1,155,070	$ (63,128)	$ (1,134)
Ending Balance (in shares) at Sep. 30, 2018	108,879,245		108,879,000	16,142,000