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
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			13,831,000
Increase (decrease) in stockholders' equity
Net income for common stock	28,462	19,189			19,189
Other comprehensive income (loss), net of taxes (tax benefits)	(1,838)	27				27
Common stock dividends	(29,412)	(17,640)			(17,640)
Balance at Mar. 31, 2011	1,496,551	1,338,974	92,224	389,609	856,405	736
Balance (in shares) at Mar. 31, 2011			13,831,000
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
Increase (decrease) in stockholders' equity
Net income for common stock	38,316	27,300			27,300
Other comprehensive income (loss), net of taxes (tax benefits)	311	77				77
Common stock dividends	(29,817)	(18,261)			(18,261)
Balance at Mar. 31, 2012	$ 1,554,098	$ 1,415,200	$ 94,911	$ 426,921	$ 893,323	$ 45
Balance (in shares) at Mar. 31, 2012	96,541,143		14,234,000