Electric utility segment - Condensed consolidating balance sheet (Details) - USD ($) $ in Thousands	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021	Dec. 31, 2020
Utility property, plant and equipment
Total property, plant and equipment, net	$ 5,411,746	$ 5,392,068
Current assets
Cash and cash equivalents	301,704	305,551	$ 277,579
Restricted cash	5,912	5,911	14,067
Other long-term assets
Operating lease right-of-use assets	136,207	122,416
Total assets	15,908,429	15,822,637
Capitalization
Common stock equity	2,303,642	2,390,884	2,321,293	$ 2,337,502
Preferred stock of subsidiaries - not subject to mandatory redemption	34,293	34,293
Current liabilities
Interest and preferred dividends payable	33,519	19,889
Deferred credits and other liabilities
Deferred income taxes	340,246	384,760
Total liabilities and shareholders’ equity	15,908,429	15,822,637
Hawaiian Electric Consolidated
Utility property, plant and equipment
Land	52,057	51,937
Plant and equipment	7,796,069	7,735,983
Less accumulated depreciation	(2,985,762)	(2,940,517)
Construction in progress	212,748	204,569
Utility property, plant and equipment, net	5,075,112	5,051,972
Nonutility property, plant and equipment, less accumulated depreciation	6,948	6,949
Total property, plant and equipment, net	5,082,060	5,058,921
Investment in wholly owned subsidiaries, at equity	0	0
Current assets
Cash and cash equivalents	29,055	52,169	51,743
Restricted cash	2,140	3,089	11,506
Advances to affiliates	0	0
Customer accounts receivable, net	181,400	186,859
Accrued unbilled revenues, net	140,005	129,155
Other accounts receivable, net	7,040	7,267
Fuel oil stock, at average cost	139,372	104,078
Materials and supplies, at average cost	72,706	71,877
Prepayments and other	41,415	46,031
Regulatory assets	78,875	66,664
Total current assets	692,008	667,189
Other long-term assets
Operating lease right-of-use assets	114,478	101,470
Regulatory assets	480,286	498,879
Other	166,344	165,166
Total other long-term assets	761,108	765,515
Total assets	6,535,176	6,491,625
Capitalization
Common stock equity	2,276,884	2,261,899	2,157,385	2,141,918
Preferred stock of subsidiaries - not subject to mandatory redemption	34,293	34,293
Long-term debt, net	1,624,599	1,624,427
Total capitalization	3,935,776	3,920,619
Current liabilities
Current portion of operating lease liabilities	39,958	49,368
Current portion of long-term debt	51,982	51,975
Short-term borrowings from non-affiliates	6,000	0
Short-term borrowings from affiliate	0	0
Accounts payable	168,189	160,007
Interest and preferred dividends payable	28,154	17,325
Taxes accrued, including revenue taxes	181,324	208,280
Regulatory liabilities	29,928	29,760
Other	80,218	71,569
Total current liabilities	585,753	588,284
Deferred credits and other liabilities
Operating lease liabilities	88,689	65,780
Deferred income taxes	406,324	408,634
Regulatory liabilities	973,516	967,008
Unamortized tax credits	101,967	103,945
Defined benefit pension and other postretirement benefit plans liability	315,675	321,780
Other	127,476	115,575
Total deferred credits and other liabilities	2,013,647	1,982,722
Total liabilities and shareholders’ equity	6,535,176	6,491,625
Hawaiian Electric Consolidated | Reportable Legal Entities | Hawaiian Electric Industries, Inc.
Utility property, plant and equipment
Land	42,857	42,737
Plant and equipment	5,144,377	5,097,033
Less accumulated depreciation	(1,788,280)	(1,757,096)
Construction in progress	164,073	159,854
Utility property, plant and equipment, net	3,563,027	3,542,528
Nonutility property, plant and equipment, less accumulated depreciation	5,301	5,302
Total property, plant and equipment, net	3,568,328	3,547,830
Investment in wholly owned subsidiaries, at equity	681,998	676,237
Current assets
Cash and cash equivalents	19,894	23,344	29,727
Restricted cash	2,140	3,089	11,506
Advances to affiliates	5,000	1,000
Customer accounts receivable, net	128,263	135,949
Accrued unbilled revenues, net	98,511	92,469
Other accounts receivable, net	15,846	18,624
Fuel oil stock, at average cost	105,780	71,184
Materials and supplies, at average cost	42,852	42,006
Prepayments and other	29,677	32,140
Regulatory assets	69,638	58,695
Total current assets	517,601	478,500
Other long-term assets
Operating lease right-of-use assets	61,826	78,710
Regulatory assets	325,063	337,903
Other	128,934	130,546
Total other long-term assets	515,823	547,159
Total assets	5,283,750	5,249,726
Capitalization
Common stock equity	2,276,884	2,261,899	2,157,385	2,141,918
Preferred stock of subsidiaries - not subject to mandatory redemption	22,293	22,293
Long-term debt, net	1,136,739	1,136,620
Total capitalization	3,435,916	3,420,812
Current liabilities
Current portion of operating lease liabilities	31,078	45,955
Current portion of long-term debt	39,986	39,981
Short-term borrowings from non-affiliates	6,000
Short-term borrowings from affiliate	12,800	0
Accounts payable	124,463	111,024
Interest and preferred dividends payable	20,057	12,442
Taxes accrued, including revenue taxes	125,425	143,723
Regulatory liabilities	19,416	22,240
Other	60,491	56,752
Total current liabilities	439,716	432,117
Deferred credits and other liabilities
Operating lease liabilities	44,785	46,426
Deferred income taxes	289,376	291,027
Regulatory liabilities	702,745	695,152
Unamortized tax credits	74,821	76,201
Defined benefit pension and other postretirement benefit plans liability	216,181	220,480
Other	80,210	67,511
Total deferred credits and other liabilities	1,408,118	1,396,797
Total liabilities and shareholders’ equity	5,283,750	5,249,726
Hawaiian Electric Consolidated | Reportable Legal Entities | Hawaii Electric Light
Utility property, plant and equipment
Land	5,606	5,606
Plant and equipment	1,394,875	1,390,361
Less accumulated depreciation	(627,421)	(619,991)
Construction in progress	19,691	17,129
Utility property, plant and equipment, net	792,751	793,105
Nonutility property, plant and equipment, less accumulated depreciation	115	115
Total property, plant and equipment, net	792,866	793,220
Investment in wholly owned subsidiaries, at equity	0	0
Current assets
Cash and cash equivalents	6,017	5,326	7,730
Restricted cash	0	0	0
Advances to affiliates	0	0
Customer accounts receivable, net	27,735	28,469
Accrued unbilled revenues, net	21,235	19,529
Other accounts receivable, net	5,128	3,347
Fuel oil stock, at average cost	13,895	12,814
Materials and supplies, at average cost	9,673	9,727
Prepayments and other	4,602	6,052
Regulatory assets	4,877	3,051
Total current assets	93,162	88,315
Other long-term assets
Operating lease right-of-use assets	38,368	22,442
Regulatory assets	78,877	81,645
Other	18,620	17,124
Total other long-term assets	135,865	121,211
Total assets	1,021,893	1,002,746
Capitalization
Common stock equity	336,177	332,900	320,494	317,451
Preferred stock of subsidiaries - not subject to mandatory redemption	7,000	7,000
Long-term debt, net	234,413	234,390
Total capitalization	577,590	574,290
Current liabilities
Current portion of operating lease liabilities	6,370	3,378
Current portion of long-term debt	11,996	11,994
Short-term borrowings from non-affiliates	0
Short-term borrowings from affiliate	5,000	1,000
Accounts payable	22,175	26,139
Interest and preferred dividends payable	3,687	2,617
Taxes accrued, including revenue taxes	29,109	33,153
Regulatory liabilities	5,495	3,247
Other	18,869	14,158
Total current liabilities	102,701	95,686
Deferred credits and other liabilities
Operating lease liabilities	32,066	19,063
Deferred income taxes	52,859	53,298
Regulatory liabilities	178,224	179,267
Unamortized tax credits	13,927	14,212
Defined benefit pension and other postretirement benefit plans liability	47,842	48,900
Other	16,684	18,030
Total deferred credits and other liabilities	341,602	332,770
Total liabilities and shareholders’ equity	1,021,893	1,002,746
Hawaiian Electric Consolidated | Reportable Legal Entities | Maui Electric
Utility property, plant and equipment
Land	3,594	3,594
Plant and equipment	1,256,817	1,248,589
Less accumulated depreciation	(570,061)	(563,430)
Construction in progress	28,984	27,586
Utility property, plant and equipment, net	719,334	716,339
Nonutility property, plant and equipment, less accumulated depreciation	1,532	1,532
Total property, plant and equipment, net	720,866	717,871
Investment in wholly owned subsidiaries, at equity	0	0
Current assets
Cash and cash equivalents	3,067	23,422	14,209
Restricted cash	0	0	0
Advances to affiliates	12,800	0
Customer accounts receivable, net	25,402	22,441
Accrued unbilled revenues, net	20,259	17,157
Other accounts receivable, net	4,269	3,031
Fuel oil stock, at average cost	19,697	20,080
Materials and supplies, at average cost	20,181	20,144
Prepayments and other	5,883	7,114
Regulatory assets	4,360	4,918
Total current assets	115,918	118,307
Other long-term assets
Operating lease right-of-use assets	14,284	318
Regulatory assets	76,346	79,331
Other	19,607	18,510
Total other long-term assets	110,237	98,159
Total assets	947,021	934,337
Capitalization
Common stock equity	345,744	343,260	311,405	309,363
Preferred stock of subsidiaries - not subject to mandatory redemption	5,000	5,000
Long-term debt, net	253,447	253,417
Total capitalization	604,191	601,677
Current liabilities
Current portion of operating lease liabilities	2,510	35
Current portion of long-term debt	0	0
Short-term borrowings from non-affiliates	0
Short-term borrowings from affiliate	0	0
Accounts payable	21,551	22,844
Interest and preferred dividends payable	4,414	2,269
Taxes accrued, including revenue taxes	25,537	30,679
Regulatory liabilities	5,017	4,273
Other	19,214	18,540
Total current liabilities	78,243	78,640
Deferred credits and other liabilities
Operating lease liabilities	11,838	291
Deferred income taxes	64,089	64,309
Regulatory liabilities	92,547	92,589
Unamortized tax credits	13,219	13,532
Defined benefit pension and other postretirement benefit plans liability	52,312	53,257
Other	30,582	30,042
Total deferred credits and other liabilities	264,587	254,020
Total liabilities and shareholders’ equity	947,021	934,337
Hawaiian Electric Consolidated | Reportable Legal Entities | Other subsidiaries
Utility property, plant and equipment
Land	0	0
Plant and equipment	0	0
Less accumulated depreciation	0	0
Construction in progress	0	0
Utility property, plant and equipment, net	0	0
Nonutility property, plant and equipment, less accumulated depreciation	0	0
Total property, plant and equipment, net	0	0
Investment in wholly owned subsidiaries, at equity	0	0
Current assets
Cash and cash equivalents	77	77	77
Restricted cash	0	0	0
Advances to affiliates	0	0
Customer accounts receivable, net	0	0
Accrued unbilled revenues, net	0	0
Other accounts receivable, net	0	0
Fuel oil stock, at average cost	0	0
Materials and supplies, at average cost	0	0
Prepayments and other	0	0
Regulatory assets	0	0
Total current assets	77	77
Other long-term assets
Operating lease right-of-use assets	0	0
Regulatory assets	0	0
Other	0	0
Total other long-term assets	0	0
Total assets	77	77
Capitalization
Common stock equity	77	77	77	77
Preferred stock of subsidiaries - not subject to mandatory redemption	0	0
Long-term debt, net	0	0
Total capitalization	77	77
Current liabilities
Current portion of operating lease liabilities	0	0
Current portion of long-term debt	0	0
Short-term borrowings from non-affiliates	0
Short-term borrowings from affiliate	0	0
Accounts payable	0	0
Interest and preferred dividends payable	0	0
Taxes accrued, including revenue taxes	0	0
Regulatory liabilities	0	0
Other	0	0
Total current liabilities	0	0
Deferred credits and other liabilities
Operating lease liabilities	0	0
Deferred income taxes	0	0
Regulatory liabilities	0	0
Unamortized tax credits	0	0
Defined benefit pension and other postretirement benefit plans liability	0	0
Other	0	0
Total deferred credits and other liabilities	0	0
Total liabilities and shareholders’ equity	77	77
Hawaiian Electric Consolidated | Consolidating adjustments
Utility property, plant and equipment
Land	0	0
Plant and equipment	0	0
Less accumulated depreciation	0	0
Construction in progress	0	0
Utility property, plant and equipment, net	0	0
Nonutility property, plant and equipment, less accumulated depreciation	0	0
Total property, plant and equipment, net	0	0
Investment in wholly owned subsidiaries, at equity	(681,998)	(676,237)
Current assets
Cash and cash equivalents	0	0	0
Restricted cash	0	0	0
Advances to affiliates	(17,800)	(1,000)
Customer accounts receivable, net	0	0
Accrued unbilled revenues, net	0	0
Other accounts receivable, net	(18,203)	(17,735)
Fuel oil stock, at average cost	0	0
Materials and supplies, at average cost	0	0
Prepayments and other	1,253	725
Regulatory assets	0	0
Total current assets	(34,750)	(18,010)
Other long-term assets
Operating lease right-of-use assets	0	0
Regulatory assets	0	0
Other	(817)	(1,014)
Total other long-term assets	(817)	(1,014)
Total assets	(717,565)	(695,261)
Capitalization
Common stock equity	(681,998)	(676,237)	$ (631,976)	$ (626,891)
Preferred stock of subsidiaries - not subject to mandatory redemption	0	0
Long-term debt, net	0	0
Total capitalization	(681,998)	(676,237)
Current liabilities
Current portion of operating lease liabilities	0	0
Current portion of long-term debt	0	0
Short-term borrowings from non-affiliates	0
Short-term borrowings from affiliate	(17,800)	(1,000)
Accounts payable	0	0
Interest and preferred dividends payable	(4)	(3)
Taxes accrued, including revenue taxes	1,253	725
Regulatory liabilities	0	0
Other	(18,356)	(17,881)
Total current liabilities	(34,907)	(18,159)
Deferred credits and other liabilities
Operating lease liabilities	0	0
Deferred income taxes	0	0
Regulatory liabilities	0	0
Unamortized tax credits	0	0
Defined benefit pension and other postretirement benefit plans liability	(660)	(857)
Other	0	(8)
Total deferred credits and other liabilities	(660)	(865)
Total liabilities and shareholders’ equity	$ (717,565)	$ (695,261)