Electric utility subsidiary - Commitments and contingencies (Details) (USD $)	3 Months Ended						3 Months Ended		0 Months Ended		1 Months Ended	3 Months Ended		1 Months Ended
	Mar. 31, 2014 item	Mar. 31, 2014 Hawaiian Electric Company	Mar. 31, 2013 Hawaiian Electric Company	Mar. 31, 2014 Maui Electric Company (MECO)	Mar. 31, 2013 Maui Electric Company (MECO)	Mar. 31, 2012 Maui Electric Company (MECO)	Mar. 31, 2014 Hawaii Electric Light Company, Inc. (HELCO)	Mar. 31, 2013 Hawaii Electric Light Company, Inc. (HELCO)	Feb. 07, 2014 Hawaiian Electric Company, Inc. and Subsidiaries	Oct. 19, 2012 Hawaiian Electric Company, Inc. and Subsidiaries	Oct. 31, 2013 Hawaiian Electric Company, Inc. and Subsidiaries	Mar. 31, 2014 Hawaiian Electric Company, Inc. and Subsidiaries	Mar. 31, 2013 Hawaiian Electric Company, Inc. and Subsidiaries	Apr. 30, 2014 Subsequent Event order	Apr. 30, 2014 Subsequent Event Hawaiian Electric Company, Inc. and Subsidiaries	Mar. 01, 2014 Maximum Hawaiian Electric Company, Inc. and Subsidiaries	Mar. 01, 2014 Minimum Hawaiian Electric Company, Inc. and Subsidiaries
Environmental regulation
Number of EGUs impacted by proposed rules of MATS	14
Period of extension resulting in MATS compliance date		1 year
Period for which operations was stopped prior to merger	4 years
Additional accrued investigation and estimated cleanup costs				$ 3,600,000		$ 3,100,000
Percentage of reduction in GHG emissions by 2020										25.00%	16.00%
Annual revenue		512,455,000	507,058,000	102,693,000	104,399,000		104,931,000	106,012,000				720,062,000	717,441,000
Asset retirement obligations
Impact on earnings from recognition of AROs												0
Changes in the asset retirement obligation liability
Balance, beginning of period												43,106,000	48,431,000
Accretion expense												370,000	124,000
Liabilities settled												(2,240,000)	(642,000)
Revisions in estimated cash flows												0	0
Balance, end of period												41,236,000	47,913,000
Baseline capital project value to determine revenue adjustment											$ 2,500,000
Proposed rate base adjustment, percent of previous rate base adjustment									90.00%
Proposed effective interest rate, revenue balancing account																3.25%	1.25%
Effective interest rate, revenue balancing account									6.00%
Regulatory response period									120 days
Number of orders from regulatory agency														4
Period to file required plan															120 days
Period to file demand response portfolio plan															90 days
Period to file implementation plan															60 days
Period for full implementation of plan															180 days
Period to file action plan															30 days
Proposal to file implementation proposal															120 days