Consolidated Statements of Changes in Common Stock Equity - HECO (USD $) In Thousands	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
Comprehensive income (loss):
Net income for common stock		35,694			35,694		35,694
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 $2,849 and $1,155 in June 2011 and June 2010, respectively	1,959	1,813				1,813	1,813
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $2,801 and $1,080 in June 2011 and June 2010, respectively	(1,697)	(1,697)				(1,697)	(1,697)
Other comprehensive income						116
Comprehensive income	58,257	35,810					35,810
Common stock dividends	(57,586)	(26,887)			(26,887)
Common stock issue expenses		(7)		(7)
Balance at Jun. 30, 2010	1,466,633	1,315,324	91,931	385,652	835,843	1,898
Balance (in shares) at Jun. 30, 2010			13,787
Balance at Mar. 31, 2010
Comprehensive income (loss):
Net income for common stock		17,642
Balance at Jun. 30, 2010		1,315,324	91,931
Balance (in shares) at Jun. 30, 2010			13,787
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			13,831
Comprehensive income (loss):
Net income for common stock		36,213			36,213		36,213
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 $2,849 and $1,155 in June 2011 and June 2010, respectively	3,488	4,426				4,426	4,426
Less: reclassification adjustment for impact of D&Os of the PUC included in regulatory assets, net of taxes of $2,801 and $1,080 in June 2011 and June 2010, respectively	(4,352)	(4,352)				(4,352)	(4,352)
Other comprehensive income						74
Comprehensive income	58,230	36,287					36,287
Common stock dividends	(58,998)	(35,279)			(35,279)
Balance at Jun. 30, 2011	1,512,207	1,338,406	92,224	389,609	855,790	783
Balance (in shares) at Jun. 30, 2011			13,831
Balance at Mar. 31, 2011
Comprehensive income (loss):
Net income for common stock		17,024
Balance at Jun. 30, 2011		$ 1,338,406	$ 92,224	$ 389,609
Balance (in shares) at Jun. 30, 2011			13,831