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	$ 1,480,394	$ 1,334,155	$ 92,224	$ 389,609	$ 851,613	$ 709
Balance (in shares) at Dec. 31, 2010			13,831,000
Increase (decrease) in stockholders' equity
Net income for common stock	104,005	74,172			74,172
Other comprehensive income, net of taxes	5,810	196				196
Common stock dividends	(88,750)	(52,919)			(52,919)
Balance at Sep. 30, 2011	1,534,515	1,355,604	92,224	389,609	872,866	905
Balance (in shares) at Sep. 30, 2011			13,831,000
Balance at Jun. 30, 2011
Increase (decrease) in stockholders' equity
Net income for common stock	48,404	37,959
Other comprehensive income, net of taxes	3,181	122
Balance at Sep. 30, 2011	1,534,515	1,355,604	92,224	389,609
Balance (in shares) at Sep. 30, 2011			13,831,000
Balance at Dec. 31, 2011	1,528,706	1,402,841	94,911	426,921	881,041	(32)
Balance (in shares) at Dec. 31, 2011	96,038,328		14,234,000
Increase (decrease) in stockholders' equity
Net income for common stock	124,822	95,051			95,051
Other comprehensive income, net of taxes	3,447	229				229
Common stock dividends	(89,902)	(54,783)			(54,783)
Balance at Sep. 30, 2012	1,607,135	1,443,338	94,911	426,921	921,309	197
Balance (in shares) at Sep. 30, 2012	97,425,467		14,234,000
Balance at Jun. 30, 2012
Increase (decrease) in stockholders' equity
Net income for common stock	47,706	38,375
Other comprehensive income, net of taxes	1,586	77
Balance at Sep. 30, 2012	$ 1,607,135	$ 1,443,338	$ 94,911	$ 426,921
Balance (in shares) at Sep. 30, 2012	97,425,467		14,234,000