SCHEDULE I - CONDENSED FINANCIAL INFORMATION OF REGISTRANT (Details) (USD $)	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009	Dec. 31, 2008
ASSETS
Cash and cash equivalents	$ 270,265,000	$ 330,651,000	$ 503,922,000	$ 183,435,000
Accounts receivable	344,322,000	266,996,000
Property, plant and equipment, net	3,334,501,000	3,165,918,000
Other assets	517,550,000	487,614,000
Total assets	9,592,731,000	9,085,344,000
Liabilities
Accounts payable	216,176,000	202,446,000
Long-term debt, net	1,340,070,000	1,364,942,000
Retirement benefits liability	530,410,000	376,994,000
Other	516,990,000	446,485,000
Total liabilities	8,026,489,000	7,567,414,000
Shareholders' equity
Preferred stock, no par value, authorized 10,000,000 shares; issued: none
Common stock, no par value, authorized 200,000,000 shares; issued and outstanding: 96,038,328 shares and 94,690,932 shares in 2011 and 2010, respectively	1,349,446,000	1,314,199,000
Retained earnings	201,640,000	181,910,000
Accumulated other comprehensive loss	(19,137,000)	(12,472,000)
Total shareholders' equity	1,531,949,000	1,483,637,000	1,441,648,000	1,389,454,000
Total liabilities and shareholders' equity	9,592,731,000	9,085,344,000
Aggregate principal payments
2012	65,000,000
2013	50,000,000
2014	111,000,000
2016	75,000,000
Self-insured United States longshore & Harbor bond
Aggregate principal payments
Guarantee obligation maximum exposure	200,000
Self-insured automobile bond
Aggregate principal payments
Guarantee obligation maximum exposure	500,000
HEI medium-term notes 4.23-6.141%, due 2011
Liabilities
Long-term debt, net		150,000,000
HEI medium-term note 7.13%, due 2012
Liabilities
Long-term debt, net	7,000,000	7,000,000
HEI medium-term note 5.25%, due 2013
Liabilities
Long-term debt, net	50,000,000	50,000,000
Shareholders' equity
Interest rate of medium-term notes (as a percent)	5.25%
HEI medium-term note 6.51%, due 2014
Liabilities
Long-term debt, net	100,000,000	100,000,000
Shareholders' equity
Interest rate of medium-term notes (as a percent)	6.51%
HEI senior note 4.41%, due 2016
Liabilities
Long-term debt, net	75,000,000
HEI senior note 5.67%, due 2021
Liabilities
Long-term debt, net	50,000,000
Hawaiian Electric Industries, Inc.
ASSETS
Cash and cash equivalents	1,765,000	1,540,000	2,915,000	7,130,000
Accounts receivable	1,361,000	1,773,000
Property, plant and equipment, net	6,076,000	582,000
Deferred income tax assets	14,208,000	12,684,000
Other assets	7,661,000	6,041,000
Investments in subsidiaries, at equity	1,902,154,000	1,838,679,000
Total assets	1,933,225,000	1,861,299,000
Liabilities
Accounts payable	3,602,000	722,000
Interest payable	5,270,000	6,826,000
Notes payable to subsidiaries	7,019,000	6,777,000
Commercial paper	68,821,000	24,923,000
Long-term debt, net	282,000,000	307,000,000
Retirement benefits liability	26,201,000	20,888,000
Other	8,363,000	10,526,000
Total liabilities	401,276,000	377,662,000
Shareholders' equity
Common stock, no par value, authorized 200,000,000 shares; issued and outstanding: 96,038,328 shares and 94,690,932 shares in 2011 and 2010, respectively	1,349,446,000	1,314,199,000
Retained earnings	201,640,000	181,910,000
Accumulated other comprehensive loss	(19,137,000)	(12,472,000)
Total shareholders' equity	1,531,949,000	1,483,637,000
Total liabilities and shareholders' equity	1,933,225,000	1,861,299,000
Aggregate principal payments
2012	7,000,000
2013	50,000,000
2014	100,000,000
2016	75,000,000
Hawaiian Electric Industries, Inc. | HEI medium-term notes 4.23-6.141%, due 2011
Liabilities
Long-term debt, net		150,000,000
Shareholders' equity
Interest rate of medium-term notes (as a percent)	4.23%	4.23%
Hawaiian Electric Industries, Inc. | HEI medium-term note 7.13%, due 2012
Liabilities
Long-term debt, net	7,000,000	7,000,000
Shareholders' equity
Interest rate of medium-term notes (as a percent)	7.13%	7.13%
Hawaiian Electric Industries, Inc. | HEI medium-term note 5.25%, due 2013
Liabilities
Long-term debt, net	50,000,000	50,000,000
Shareholders' equity
Interest rate of medium-term notes (as a percent)	5.25%	5.25%
Hawaiian Electric Industries, Inc. | HEI medium-term note 6.51%, due 2014
Liabilities
Long-term debt, net	100,000,000	100,000,000
Shareholders' equity
Interest rate of medium-term notes (as a percent)	6.51%	6.51%
Hawaiian Electric Industries, Inc. | HEI senior note 4.41%, due 2016
Liabilities
Long-term debt, net	75,000,000
Shareholders' equity
Interest rate of medium-term notes (as a percent)	4.41%
Hawaiian Electric Industries, Inc. | HEI senior note 5.67%, due 2021
Liabilities
Long-term debt, net	$ 50,000,000
Shareholders' equity
Interest rate of medium-term notes (as a percent)	5.67%