Electric utility segment (Details 10) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2013	Sep. 30, 2013	Jun. 30, 2013	Mar. 31, 2013	Dec. 31, 2012	Sep. 30, 2012	Jun. 30, 2012	Mar. 31, 2012	Dec. 31, 2013	Dec. 31, 2012	Dec. 31, 2011
Beginning Balance				$ 1,593,865,000				$ 1,528,706,000	$ 1,593,865,000	$ 1,528,706,000	$ 1,480,394,000
Net income for common stock	39,013,000	48,236,000	40,588,000	33,679,000	13,836,000	47,706,000	38,800,000	38,316,000	161,516,000	138,658,000	138,230,000
Other comprehensive income (loss), net of taxes									9,673,000	(7,286,000)	(6,665,000)
Issuance of common stock, net of expenses									41,692,000	41,295,000	21,217,000
Common stock dividends									(122,626,000)	(120,150,000)	(118,500,000)
Ending Balance	1,727,070,000				1,593,865,000				1,727,070,000	1,593,865,000	1,528,706,000
HECO
Beginning Balance				1,472,136,000				1,402,841,000	1,472,136,000	1,402,841,000	1,334,155,000
Net income for common stock									122,929,000	99,276,000	99,986,000
Other comprehensive income (loss), net of taxes									1,578,000	(938,000)	(741,000)
Issuance of common stock, net of expenses									78,499,000	44,001,000	39,999,000
Common stock dividends									(81,578,000)	(73,044,000)	(70,558,000)
Ending Balance	1,593,564,000				1,472,136,000				1,593,564,000	1,472,136,000	1,402,841,000
HELCO
Beginning Balance				268,908,000				280,468,000	268,908,000	280,468,000	269,986,000
Net income for common stock									20,136,000	16,212,000	26,651,000
Other comprehensive income (loss), net of taxes									145,000	(34,000)	(45,000)
Issuance of common stock, net of expenses											0
Common stock dividends									(14,387,000)	(27,738,000)	(16,124,000)
Ending Balance	274,802,000				268,908,000				274,802,000	268,908,000	280,468,000
MECO
Beginning Balance				228,927,000				235,568,000	228,927,000	235,568,000	229,651,000
Net income for common stock									21,277,000	12,627,000	17,974,000
Other comprehensive income (loss), net of taxes									99,000	(71,000)	(53,000)
Issuance of common stock, net of expenses											0
Common stock dividends									(1,532,000)	(19,197,000)	(12,004,000)
Ending Balance	248,771,000				228,927,000				248,771,000	228,927,000	235,568,000
RHI
Beginning Balance				104,000				107,000	104,000	107,000	91,000
Net income for common stock									(3,000)	(3,000)	(9,000)
Other comprehensive income (loss), net of taxes											0
Issuance of common stock, net of expenses											25,000
Ending Balance	101,000				104,000				101,000	104,000	107,000
Consolidating adjustments
Beginning Balance				(497,939,000)				(516,143,000)	(497,939,000)	(516,143,000)	(499,728,000)
Net income for common stock									(41,410,000)	(28,836,000)	(44,616,000)
Other comprehensive income (loss), net of taxes									(244,000)	105,000	98,000
Issuance of common stock, net of expenses										0	(25,000)
Common stock dividends									15,919,000	46,935,000	28,128,000
Ending Balance	(523,674,000)				(497,939,000)				(523,674,000)	(497,939,000)	(516,143,000)
HECO Consolidated
Beginning Balance				1,472,136,000				1,402,841,000	1,472,136,000	1,402,841,000	1,334,155,000
Net income for common stock	31,990,000	37,817,000	28,693,000	24,429,000	4,225,000	38,375,000	29,376,000	27,300,000	122,929,000	99,276,000	99,986,000
Other comprehensive income (loss), net of taxes									1,578,000	(938,000)	(741,000)
Issuance of common stock, net of expenses									78,499,000	44,001,000	39,999,000
Common stock dividends									(81,578,000)	(73,044,000)	(70,558,000)
Ending Balance	$ 1,593,564,000				$ 1,472,136,000				$ 1,593,564,000	$ 1,472,136,000	$ 1,402,841,000