Electric utility segment - Condensed consolidating statement of income (Details) - USD ($) $ in Thousands	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021
Condensed Income Statements, Captions [Line Items]
Revenues	$ 785,068	$ 642,946
Expenses
Total expenses	685,792	544,915
Total operating income	99,276	98,031
Allowance for equity funds used during construction	2,409	2,191
Retirement defined benefits credit—other than service costs	1,243	2,435
Allowance for borrowed funds used during construction	778	747
Income before income taxes	87,480	80,196
Income taxes	17,840	15,365
Net income attributable to Hawaiian Electric	69,640	64,831
Preferred stock dividends of Hawaiian Electric	473	473
Net income for common stock	69,167	64,358
Hawaiian Electric Consolidated
Condensed Income Statements, Captions [Line Items]
Revenues	708,792	564,864
Expenses
Fuel oil	221,286	127,427
Purchased power	163,533	142,296
Other operation and maintenance	125,257	114,570
Depreciation	58,471	57,355
Taxes, other than income taxes	66,650	54,102
Total expenses	635,197	495,750
Total operating income	73,595	69,114
Allowance for equity funds used during construction	2,409	2,191
Equity in earnings of subsidiaries	0	0
Retirement defined benefits credit—other than service costs	990	1,021
Interest expense and other charges, net	(18,326)	(17,983)
Allowance for borrowed funds used during construction	778	747
Income before income taxes	59,446	55,090
Income taxes	12,538	11,233
Net income	46,908	43,857
Preferred stock dividends of subsidiaries	229	229
Net income attributable to Hawaiian Electric	46,679	43,628
Preferred stock dividends of Hawaiian Electric	270	270
Net income for common stock	46,409	43,358
Hawaiian Electric Consolidated | Reportable Legal Entities | Hawaiian Electric Industries, Inc.
Condensed Income Statements, Captions [Line Items]
Revenues	500,242	400,554
Expenses
Fuel oil	154,425	88,728
Purchased power	124,183	108,604
Other operation and maintenance	83,656	77,335
Depreciation	39,484	38,914
Taxes, other than income taxes	47,274	38,627
Total expenses	449,022	352,208
Total operating income	51,220	48,346
Allowance for equity funds used during construction	1,990	1,748
Equity in earnings of subsidiaries	13,661	12,510
Retirement defined benefits credit—other than service costs	855	886
Interest expense and other charges, net	(13,093)	(12,832)
Allowance for borrowed funds used during construction	651	591
Income before income taxes	55,284	51,249
Income taxes	8,605	7,621
Net income	46,679	43,628
Preferred stock dividends of subsidiaries	0	0
Net income attributable to Hawaiian Electric	46,679	43,628
Preferred stock dividends of Hawaiian Electric	270	270
Net income for common stock	46,409	43,358
Hawaiian Electric Consolidated | Reportable Legal Entities | Hawaii Electric Light
Condensed Income Statements, Captions [Line Items]
Revenues	108,528	85,149
Expenses
Fuel oil	25,251	16,485
Purchased power	30,712	21,597
Other operation and maintenance	20,214	17,912
Depreciation	10,351	10,048
Taxes, other than income taxes	10,032	7,993
Total expenses	96,560	74,035
Total operating income	11,968	11,114
Allowance for equity funds used during construction	193	132
Equity in earnings of subsidiaries	0	0
Retirement defined benefits credit—other than service costs	167	168
Interest expense and other charges, net	(2,609)	(2,581)
Allowance for borrowed funds used during construction	60	44
Income before income taxes	9,779	8,877
Income taxes	2,268	2,051
Net income	7,511	6,826
Preferred stock dividends of subsidiaries	134	134
Net income attributable to Hawaiian Electric	7,377	6,692
Preferred stock dividends of Hawaiian Electric	0	0
Net income for common stock	7,377	6,692
Hawaiian Electric Consolidated | Reportable Legal Entities | Maui Electric
Condensed Income Statements, Captions [Line Items]
Revenues	100,028	79,181
Expenses
Fuel oil	41,610	22,214
Purchased power	8,638	12,095
Other operation and maintenance	21,387	19,323
Depreciation	8,636	8,393
Taxes, other than income taxes	9,344	7,482
Total expenses	89,615	69,507
Total operating income	10,413	9,674
Allowance for equity funds used during construction	226	311
Equity in earnings of subsidiaries	0	0
Retirement defined benefits credit—other than service costs	(32)	(33)
Interest expense and other charges, net	(2,630)	(2,590)
Allowance for borrowed funds used during construction	67	112
Income before income taxes	8,044	7,474
Income taxes	1,665	1,561
Net income	6,379	5,913
Preferred stock dividends of subsidiaries	95	95
Net income attributable to Hawaiian Electric	6,284	5,818
Preferred stock dividends of Hawaiian Electric	0	0
Net income for common stock	6,284	5,818
Hawaiian Electric Consolidated | Reportable Legal Entities | Other subsidiaries
Condensed Income Statements, Captions [Line Items]
Revenues	0	0
Expenses
Fuel oil	0	0
Purchased power	0	0
Other operation and maintenance	0	0
Depreciation	0	0
Taxes, other than income taxes	0	0
Total expenses	0	0
Total operating income	0	0
Allowance for equity funds used during construction	0	0
Equity in earnings of subsidiaries	0	0
Retirement defined benefits credit—other than service costs	0	0
Interest expense and other charges, net	0	0
Allowance for borrowed funds used during construction	0	0
Income before income taxes	0	0
Income taxes	0	0
Net income	0	0
Preferred stock dividends of subsidiaries	0	0
Net income attributable to Hawaiian Electric	0	0
Preferred stock dividends of Hawaiian Electric	0	0
Net income for common stock	0	0
Hawaiian Electric Consolidated | Consolidating adjustments
Condensed Income Statements, Captions [Line Items]
Revenues	(6)	(20)
Expenses
Fuel oil	0	0
Purchased power	0	0
Other operation and maintenance	0	0
Depreciation	0	0
Taxes, other than income taxes	0	0
Total expenses	0	0
Total operating income	(6)	(20)
Allowance for equity funds used during construction	0	0
Equity in earnings of subsidiaries	(13,661)	(12,510)
Retirement defined benefits credit—other than service costs	0	0
Interest expense and other charges, net	6	20
Allowance for borrowed funds used during construction	0	0
Income before income taxes	(13,661)	(12,510)
Income taxes	0	0
Net income	(13,661)	(12,510)
Preferred stock dividends of subsidiaries	0	0
Net income attributable to Hawaiian Electric	(13,661)	(12,510)
Preferred stock dividends of Hawaiian Electric	0	0
Net income for common stock	$ (13,661)	$ (12,510)