Consolidated Statements of Income - HECO Statement - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2020	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Revenues	$ 652,217	$ 641,427	$ 608,945	$ 677,186	$ 725,966	$ 770,882	$ 715,485	$ 661,615	$ 2,579,775	$ 2,873,948	$ 2,860,849
Expenses
Total expenses									2,268,282	2,525,927	2,527,493
Operating income	80,674	99,561	71,556	59,702	100,795	96,655	72,634	77,937	311,493	348,021	333,356
Allowance for equity funds used during construction									8,768	11,987	10,877
Retirement defined benefits expense—other than service costs									(3,210)	(2,806)	(5,962)
Allowance for borrowed funds used during construction									2,992	4,453	4,867
Income before income taxes									240,624	271,409	254,461
Income taxes									40,910	51,637	50,797
Net income (loss)	50,958	65,503	49,360	33,893	66,736	63,890	42,985	46,161	199,714	219,772	203,664
Preferred stock dividends of subsidiaries									1,890	1,890	1,890
Net income for common stock	50,485	65,032	48,887	33,420	66,263	63,419	42,512	45,688	197,824	217,882	201,774
Hawaiian Electric Company, Inc. and Subsidiaries
Revenues	571,095	562,568	534,215	597,442	645,333	688,330	633,784	578,495	2,265,320	2,545,942	2,546,525
Expenses
Fuel oil									515,274	720,709	760,528
Purchased power									568,749	633,256	639,307
Other operation and maintenance									474,192	481,737	461,491
Depreciation									222,733	215,731	203,626
Taxes, other than income taxes									215,822	240,131	239,912
Total expenses									1,996,770	2,291,564	2,304,864
Operating income	68,273	88,518	67,801	43,958	70,331	71,793	55,694	56,560	268,550	254,378	241,661
Allowance for equity funds used during construction									8,768	11,987	10,877
Retirement defined benefits expense—other than service costs									(763)	(2,836)	(3,631)
Interest expense and other charges, net									(67,794)	(70,842)	(73,348)
Allowance for borrowed funds used during construction									2,992	4,453	4,867
Income before income taxes									211,753	197,140	180,426
Income taxes									40,418	38,305	34,778
Net income (loss)	43,540	60,563	42,828	24,404	45,860	47,277	33,073	32,625	171,335	158,835	145,648
Preferred stock dividends of subsidiaries									915	915	915
Net income attributable to Hawaiian Electric									170,420	157,920	144,733
Preferred stock dividends of Hawaiian Electric									1,080	1,080	1,080
Net income for common stock	$ 43,041	$ 60,065	$ 42,329	$ 23,905	$ 45,361	$ 46,779	$ 32,574	$ 32,126	$ 169,340	$ 156,840	$ 143,653