Consolidating financial information (Details 4) - HECO (USD $) In Thousands, unless otherwise specified	3 Months Ended		6 Months Ended
	Jun. 30, 2012	Jun. 30, 2011	Jun. 30, 2012	Jun. 30, 2011
Balance			$ 1,528,706	$ 1,480,394
Net income (loss) for common stock	38,800	27,139	77,116	55,601
Other comprehensive income (loss), net of taxes (tax benefits)	1,550	4,467	1,861	2,629
Common stock dividends			(59,791)	(58,998)
Balance	1,575,776	1,508,964	1,575,776	1,508,964
HECO
Balance			1,402,841	1,334,155
Net income (loss) for common stock	29,376	17,024	56,676	36,213
Other comprehensive income (loss), net of taxes (tax benefits)	75	47	152	74
Common stock dividends			(36,522)	(35,279)
Common stock issue expenses			1
Balance	1,423,148	1,335,163	1,423,148	1,335,163
HELCO
Balance			280,468	269,986
Net income (loss) for common stock	4,491	6,575	11,102	13,192
Other comprehensive income (loss), net of taxes (tax benefits)	7	1	13	1
Common stock dividends			(6,569)	(8,061)
Balance	285,014	275,118	285,014	275,118
MECO
Balance			235,568	229,651
Net income (loss) for common stock	3,760	4,389	5,640	9,267
Other comprehensive income (loss), net of taxes (tax benefits)	6	2	12	(1)
Common stock dividends			(4,373)	(6,002)
Balance	236,847	232,915	236,847	232,915
RHI
Balance			81	86
Net income (loss) for common stock			(1)	(2)
Balance	80	84	80	84
UBC
Balance			26	5
Net income (loss) for common stock	(1)	(1)	(1)	(4)
Capital contribution from parent				25
Balance	25	26	25	26
Reclassifications and eliminations
Balance			(516,143)	(499,728)
Net income (loss) for common stock	(8,250)	(10,963)	(16,740)	(22,453)
Other comprehensive income (loss), net of taxes (tax benefits)	(13)	(3)	(25)
Common stock dividends			10,942	14,063
Capital contribution from parent				(25)
Balance	(521,966)	(508,143)	(521,966)	(508,143)
HECO Consolidated
Balance			1,402,841	1,334,155
Net income (loss) for common stock	29,376	17,024	56,676	36,213
Other comprehensive income (loss), net of taxes (tax benefits)	75	47	152	74
Common stock dividends			(36,522)	(35,279)
Common stock issue expenses			1
Balance	$ 1,423,148	$ 1,335,163	$ 1,423,148	$ 1,335,163