Quarterly information (unaudited) (Details) (USD $)	3 Months Ended								12 Months Ended
	Dec. 31, 2011	Sep. 30, 2011	Jun. 30, 2011	Mar. 31, 2011	Dec. 31, 2010	Sep. 30, 2010	Jun. 30, 2010	Mar. 31, 2010	Dec. 31, 2011	Dec. 31, 2010	Dec. 31, 2009
Quarterly information (unaudited)
Revenues	$ 851,028,000	$ 886,355,000	$ 794,319,000	$ 710,633,000	$ 695,737,000	$ 694,541,000	$ 655,664,000	$ 619,040,000	$ 3,242,335,000	$ 2,664,982,000	$ 2,309,590,000
Operating income	68,170,000	94,490,000	63,661,000	63,375,000	59,242,000	72,631,000	63,631,000	60,707,000	289,696,000	256,211,000	187,664,000
Net income for common stock	34,225,000	48,404,000	27,139,000	28,462,000	24,698,000	32,449,000	29,262,000	27,126,000	138,230,000	113,535,000	83,011,000
Basic earnings per common share (in dollars per share)	$ 0.36	$ 0.50	$ 0.28	$ 0.30	$ 0.26	$ 0.35	$ 0.31	$ 0.29	$ 1.45	$ 1.22	$ 0.91
Diluted earnings per common share (in dollars per share)	$ 0.36	$ 0.50	$ 0.28	$ 0.30	$ 0.26	$ 0.35	$ 0.31	$ 0.29	$ 1.44	$ 1.21	$ 0.91
Dividends per common share (in dollars per share)	$ 0.31	$ 0.31	$ 0.31	$ 0.31	$ 0.31	$ 0.31	$ 0.31	$ 0.31	$ 1.24	$ 1.24	$ 1.24
Market price per common share
High end of range (in dollars per share)	$ 26.79	$ 24.95	$ 26.38	$ 26.40	$ 23.41	$ 24.99	$ 24.04	$ 23.01	$ 26.79	$ 24.99
Low end of range (in dollars per share)	$ 22.91	$ 20.59	$ 23.25	$ 22.79	$ 21.77	$ 22.04	$ 21.07	$ 18.63	$ 20.59	$ 18.63
Net income for common stock
Interest income (net of taxes) at the utilities due to a federal tax settlement					6,000,000
Taxes for the write-off deferred tax asset					2,000,000
Hawaiian Electric Company and Subsidiaries
Quarterly information (unaudited)
Operating income									215,134,000	178,388,000	169,671,000
Net income for common stock									99,986,000	76,589,000	79,446,000
Quarterly results
Impairment (net of taxes) of HECO transmission project	6,000,000
Decrease in revenue	6,000,000
Decrease in net income	$ 3,000,000