Recent accounting pronouncements (Details) - USD ($) $ in Thousands	Jun. 30, 2016	Dec. 31, 2015
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets	$ 436,479	$ 480,457
Total assets	11,979,239	11,782,018
Liabilities and Equity	11,979,239	11,782,018
Long-term debt, net—other than bank	1,578,842	1,578,368
Total liabilities	9,978,764	9,820,085
Hawaiian Electric Company, Inc. and Subsidiaries
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets	5,721,853	5,672,210
Liabilities and Equity	5,721,853	5,672,210
Unamortized debt expense	344	497
Total other long-term assets	867,412	900,483
Long-term debt, net	1,279,123	1,278,702
Total capitalization	3,056,422	3,041,320
Hawaiian Electric Company
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets	4,532,647	4,476,175
Liabilities and Equity	4,532,647	4,476,175
Unamortized debt expense	249	359
Total other long-term assets	630,272	657,047
Long-term debt, net	875,443	875,163
Total capitalization	2,640,742	2,625,781
HELCO
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets	956,842	954,515
Liabilities and Equity	956,842	954,515
Unamortized debt expense	46	74
Total other long-term assets	125,200	129,329
Long-term debt, net	213,640	213,580
Total capitalization	515,915	513,282
Maui Electric
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets	841,420	830,160
Liabilities and Equity	841,420	830,160
Unamortized debt expense	49	64
Total other long-term assets	111,940	114,107
Long-term debt, net	190,040	189,959
Total capitalization	$ 461,863	458,684
Scenario, Previously Reported
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets		488,635
Total assets		11,790,196
Liabilities and Equity		11,790,196
Long-term debt, net—other than bank		1,586,546
Total liabilities		9,828,263
Scenario, Previously Reported | Hawaiian Electric Company, Inc. and Subsidiaries
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets		5,680,054
Liabilities and Equity		5,680,054
Unamortized debt expense		8,341
Total other long-term assets		908,327
Long-term debt, net		1,286,546
Total capitalization		3,049,164
Scenario, Previously Reported | Hawaiian Electric Company
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets		4,481,558
Liabilities and Equity		4,481,558
Unamortized debt expense		5,742
Total other long-term assets		662,430
Long-term debt, net		880,546
Total capitalization		2,631,164
Scenario, Previously Reported | HELCO
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets		955,935
Liabilities and Equity		955,935
Unamortized debt expense		1,494
Total other long-term assets		130,749
Long-term debt, net		215,000
Total capitalization		514,702
Scenario, Previously Reported | Maui Electric
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets		831,201
Liabilities and Equity		831,201
Unamortized debt expense		1,105
Total other long-term assets		115,148
Long-term debt, net		191,000
Total capitalization		459,725
Restatement Adjustment
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Liabilities and Equity		(8,178)
Restatement Adjustment | Hawaiian Electric Company, Inc. and Subsidiaries
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Liabilities and Equity		(7,844)
Restatement Adjustment | Hawaiian Electric Company
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Liabilities and Equity		(5,383)
Restatement Adjustment | HELCO
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Liabilities and Equity		(1,420)
Restatement Adjustment | Maui Electric
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Liabilities and Equity		(1,041)
Restatement Adjustment | Accounting Standards Update 2015-03
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Other assets		(8,178)
Total assets		(8,178)
Long-term debt, net—other than bank		(8,178)
Total liabilities		(8,178)
Restatement Adjustment | Accounting Standards Update 2015-03 | Hawaiian Electric Company, Inc. and Subsidiaries
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets		(7,844)
Unamortized debt expense		(7,844)
Total other long-term assets		(7,844)
Long-term debt, net		(7,844)
Total capitalization		(7,844)
Restatement Adjustment | Accounting Standards Update 2015-03 | Hawaiian Electric Company
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets		(5,383)
Unamortized debt expense		(5,383)
Total other long-term assets		(5,383)
Long-term debt, net		(5,383)
Total capitalization		(5,383)
Restatement Adjustment | Accounting Standards Update 2015-03 | HELCO
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets		(1,420)
Unamortized debt expense		(1,420)
Total other long-term assets		(1,420)
Long-term debt, net		(1,420)
Total capitalization		(1,420)
Restatement Adjustment | Accounting Standards Update 2015-03 | Maui Electric
New Accounting Pronouncements or Change in Accounting Principle [Line Items]
Total assets		(1,041)
Unamortized debt expense		(1,041)
Total other long-term assets		(1,041)
Long-term debt, net		(1,041)
Total capitalization		$ (1,041)