Consolidated Statements of Changes in Common Stock Equity - HECO (USD $) In Thousands, except Share data	Total	Hawaiian Electric Company, Inc. and Subsidiaries	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
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 (loss):
Net income for common stock	88,837	57,674			57,674		57,674
Retirement benefit plans:
Less: amortization of net loss, prior service gain and transition obligation included in net periodic benefit cost, net of tax benefits of $3,999 and $1,796 in September 2011 and September 2010, respectively	3,034	2,819				2,819	2,819
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,875 and $1,681 in September 2011 and September 2010, respectively	(2,640)	(2,640)				(2,640)	(2,640)
Other comprehensive income		179				179
Comprehensive income	88,077	57,853					57,853
Common stock dividends	(86,625)	(38,360)			(38,360)
Common stock issue expenses		(9)		(9)
Balance at Sep. 30, 2010	1,479,653	1,325,892	91,931	385,650	846,350	1,961
Balance (in shares) at Sep. 30, 2010			13,787,000
Balance at Jun. 30, 2010
Comprehensive income (loss):
Net income for common stock	32,449	21,980
Balance at Sep. 30, 2010	1,479,653	1,325,892	91,931
Balance (in shares) at Sep. 30, 2010			13,787,000
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 (loss):
Net income for common stock	104,005	74,172			74,172		74,172
Retirement benefit plans:
Less: amortization of net loss, prior service gain and transition obligation included in net periodic benefit cost, net of tax benefits of $3,999 and $1,796 in September 2011 and September 2010, respectively	5,556	6,280				6,280	6,280
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $3,875 and $1,681 in September 2011 and September 2010, respectively	(6,084)	(6,084)				(6,084)	(6,084)
Other comprehensive income		196				196
Comprehensive income	109,815	74,368					74,368
Common stock dividends	(88,750)	(52,919)			(52,919)
Balance at Sep. 30, 2011	1,537,758	1,358,847	92,224	389,609	876,109	905
Balance (in shares) at Sep. 30, 2011	95,975,524		13,831,000
Balance at Jun. 30, 2011
Comprehensive income (loss):
Net income for common stock	48,404	37,959
Balance at Sep. 30, 2011	$ 1,537,758	$ 1,358,847	$ 92,224	$ 389,609
Balance (in shares) at Sep. 30, 2011	95,975,524		13,831,000