Consolidated Statements of Changes in Common Stock Equity - HECO (USD $) In Thousands, except Share data, unless otherwise specified	Total	Hawaiian Electric Company, Inc. and Subsidiaries	Common stock. Hawaiian Electric Company, Inc. and Subsidiaries	Premium on capital stock Hawaiian Electric Company, Inc. and Subsidiaries	Retained earnings Hawaiian Electric Company, Inc. and Subsidiaries	Accumulated other comprehensive income (loss) Hawaiian Electric Company, Inc. and Subsidiaries	Comprehensive income Hawaiian Electric Company, Inc. and Subsidiaries
Balance at Dec. 31, 2008	$ 1,389,454	$ 1,188,842	$ 85,387	$ 299,214	$ 802,590	$ 1,651
Balance (in shares) at Dec. 31, 2008			12,806,000
Comprehensive income:
Net income for common stock	83,011	79,446			79,446		79,446
Retirement benefit plans:
Net transition asset arising during the period, net of taxes of $4,172	6,549	6,549				6,549	6,549
Prior service credit arising during the period, net of taxes of $4,408, $3,001 and $922 in 2011, 2010 and 2009, respectively	1,446	1,446				1,446	1,446
Net gains (losses) arising during the period, net of tax benefits of $74,346, $27,408 and $36,990 in 2011, 2010 and 2009, respectively	64,547	58,081				58,081	58,081
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $5,332, $2,387 and $6,250 in 2011, 2010 and 2009, respectively	10,754	9,811				9,811	9,811
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of tax benefits of $64,134, $21,336 and $48,251 in 2011, 2010 and 2009, respectively	(75,756)	(75,756)				(75,756)	(75,756)
Other comprehensive income (loss)						131
Comprehensive income	132,085	79,577					79,577
Issuance of common stock, net of expenses	92,989	92,989	6,544	86,445
Issuance of common stock, net of expenses (in shares)			981,000
Common stock dividends	(113,419)	(55,000)			(55,000)
Balance at Dec. 31, 2009	1,441,648	1,306,408	91,931	385,659	827,036	1,782
Balance (in shares) at Dec. 31, 2009			13,787,000
Comprehensive income:
Net income for common stock	113,535	76,589			76,589		76,589
Retirement benefit plans:
Prior service credit arising during the period, net of taxes of $4,408, $3,001 and $922 in 2011, 2010 and 2009, respectively	4,712	4,712				4,712	4,712
Net gains (losses) arising during the period, net of tax benefits of $74,346, $27,408 and $36,990 in 2011, 2010 and 2009, respectively	(44,626)	(43,031)				(43,031)	(43,031)
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $5,332, $2,387 and $6,250 in 2011, 2010 and 2009, respectively	4,030	3,747				3,747	3,747
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of tax benefits of $64,134, $21,336 and $48,251 in 2011, 2010 and 2009, respectively	33,499	33,499				33,499	33,499
Other comprehensive income (loss)						(1,073)
Comprehensive income	108,785	75,516					75,516
Issuance of common stock, net of expenses		4,243	293	3,950
Issuance of common stock, net of expenses (in shares)			44,000
Common stock dividends	(115,838)	(48,769)			(48,769)
Balance at Dec. 31, 2010	1,483,637	1,337,398	92,224	389,609	854,856	709
Balance (in shares) at Dec. 31, 2010	94,690,932		13,831,000
Comprehensive income:
Net income for common stock	138,230	99,986			99,986		99,986
Retirement benefit plans:
Prior service credit arising during the period, net of taxes of $4,408, $3,001 and $922 in 2011, 2010 and 2009, respectively	6,943	6,921				6,921	6,921
Net gains (losses) arising during the period, net of tax benefits of $74,346, $27,408 and $36,990 in 2011, 2010 and 2009, respectively	(130,191)	(116,726)				(116,726)	(116,726)
Less: amortization of transition obligation, prior service credit and net losses recognized during the period in net periodic benefit cost, net of tax benefits of $5,332, $2,387 and $6,250 in 2011, 2010 and 2009, respectively	9,364	8,372				8,372	8,372
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of tax benefits of $64,134, $21,336 and $48,251 in 2011, 2010 and 2009, respectively	100,692	100,692				100,692	100,692
Other comprehensive income (loss)						(741)
Comprehensive income	131,565	99,245					99,245
Issuance of common stock, net of expenses		39,999	2,687	37,312
Issuance of common stock, net of expenses (in shares)			403,000
Common stock dividends	(118,500)	(70,558)			(70,558)
Balance at Dec. 31, 2011	$ 1,531,949	$ 1,406,084	$ 94,911	$ 426,921	$ 884,284	$ (32)
Balance (in shares) at Dec. 31, 2011	96,038,328		14,234,000