Revenues (Details) - USD ($) $ in Thousands	3 Months Ended								12 Months Ended
	Dec. 31, 2019	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Dec. 31, 2018	Sep. 30, 2018	Jun. 30, 2018	Mar. 31, 2018	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Revenue from Contract with Customer [Abstract]
General payment period									30 days
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									$ 2,622,025	$ 2,614,831
Revenue Not from Contract with Customer									252,576	246,018
Revenues	$ 725,966	$ 771,535	$ 715,485	$ 661,615	$ 761,650	$ 768,048	$ 685,277	$ 645,874	2,874,601	2,860,849	$ 2,555,625
Services/goods transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									46,659	47,300
Services/goods transferred over time
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									2,575,366	2,567,531
Electric energy sales - residential
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									807,652	801,846
Electric energy sales - commercial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									846,110	853,672
Electric energy sales - large light and power
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									905,308	894,770
Electric energy sales - other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									16,296	17,243
Bank fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									46,659	47,300
Regulatory revenue
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									(54,101)	(37,687)
Bank interest and dividend income
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									266,554	258,225
Other bank noninterest income
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									15,357	8,750
Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									24,766	16,730
Hawaiian Electric Company, Inc. and Subsidiaries
Disaggregation of Revenue [Line Items]
Revenue taxes, other than income tax expense									226,000	226,000	202,000
Revenue taxes accrued	$ 132,000				$ 130,000				132,000	130,000
Electric utility
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									2,575,366	2,567,531
Revenue Not from Contract with Customer									(29,424)	(21,006)
Revenues									2,545,942	2,546,525	2,257,566
Electric utility | Services/goods transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0
Electric utility | Services/goods transferred over time
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									2,575,366	2,567,531
Electric utility | Electric energy sales - residential
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									807,652	801,846
Electric utility | Electric energy sales - commercial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									846,110	853,672
Electric utility | Electric energy sales - large light and power
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									905,308	894,770
Electric utility | Electric energy sales - other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									16,296	17,243
Electric utility | Bank fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0
Electric utility | Regulatory revenue
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									(54,101)	(37,687)
Electric utility | Bank interest and dividend income
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									0	0
Electric utility | Other bank noninterest income
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									0	0
Electric utility | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									24,677	16,681
Bank
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									46,659	47,300
Revenue Not from Contract with Customer									281,911	266,975
Revenues									328,570	314,275	297,640
Bank | Services/goods transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									46,659	47,300
Bank | Services/goods transferred over time
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0
Bank | Electric energy sales - residential
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0
Bank | Electric energy sales - commercial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0
Bank | Electric energy sales - large light and power
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0
Bank | Electric energy sales - other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0
Bank | Bank fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									46,659	47,300
Bank | Regulatory revenue
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									0	0
Bank | Bank interest and dividend income
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									266,554	258,225
Bank | Other bank noninterest income
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									15,357	8,750
Bank | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									0	0
Other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0
Revenue Not from Contract with Customer									89	49
Revenues									89	49	$ 419
Other | Services/goods transferred at a point in time
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0
Other | Services/goods transferred over time
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0
Other | Electric energy sales - residential
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0
Other | Electric energy sales - commercial
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0
Other | Electric energy sales - large light and power
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0
Other | Electric energy sales - other
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0
Other | Bank fees
Disaggregation of Revenue [Line Items]
Revenues from contracts with customers									0	0
Other | Regulatory revenue
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									0	0
Other | Bank interest and dividend income
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									0	0
Other | Other bank noninterest income
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									0	0
Other | Other
Disaggregation of Revenue [Line Items]
Revenue Not from Contract with Customer									$ 89	$ 49