Electric utility segment Regulatory Assets and Liabilities (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2015	Dec. 31, 2014
Regulatory liabilities
Regulatory liabilities	$ 371,543	$ 344,849
Hawaiian Electric Company, Inc. and Subsidiaries
Regulatory assets
Regulatory assets	896,731	905,264
Regulatory liabilities
Regulatory liabilities	371,543	344,849
Hawaiian Electric Company, Inc. and Subsidiaries | Cost of removal in excess of salvage value
Regulatory liabilities
Regulatory liabilities	357,825	331,000
Hawaiian Electric Company, Inc. and Subsidiaries | Retirement benefit plans, regulatory liabilities
Regulatory liabilities
Regulatory liabilities	$ 9,835	12,413
Authorized amortization or recovery periods	5 years
Hawaiian Electric Company, Inc. and Subsidiaries | Other, regulatory liabilities
Regulatory liabilities
Regulatory liabilities	$ 3,883	1,436
Authorized amortization or recovery periods	5 years
Hawaiian Electric Company, Inc. and Subsidiaries | Retirement benefit plans, regulatory assets
Regulatory assets
Regulatory assets	$ 679,766	683,243
Hawaiian Electric Company, Inc. and Subsidiaries | Income taxes, net
Regulatory assets
Regulatory assets	88,039	86,836
Hawaiian Electric Company, Inc. and Subsidiaries | Decoupling revenue balancing account
Regulatory assets
Regulatory assets	74,462	91,353
Hawaiian Electric Company, Inc. and Subsidiaries | Unamortized expense and premiums on retired debt and equity issuances
Regulatory assets
Regulatory assets	14,089	15,569
Hawaiian Electric Company, Inc. and Subsidiaries | Vacation earned, but not yet taken
Regulatory assets
Regulatory assets	$ 10,420	10,248
Authorized amortization or recovery periods	1 year
Hawaiian Electric Company, Inc. and Subsidiaries | Postretirement benefits other than pensions
Regulatory assets
Regulatory assets	$ 0	18
Authorized amortization or recovery periods	18 years
Remaining amortization or recovery periods	1 year
Hawaiian Electric Company, Inc. and Subsidiaries | Other, regulatory assets
Regulatory assets
Regulatory assets	$ 29,955	17,997
Hawaiian Electric Company, Inc. and Subsidiaries | Minimum | Cost of removal in excess of salvage value
Regulatory liabilities
Authorized amortization or recovery periods	1 year
Hawaiian Electric Company, Inc. and Subsidiaries | Minimum | Other, regulatory liabilities
Regulatory liabilities
Remaining amortization or recovery periods	1 year
Hawaiian Electric Company, Inc. and Subsidiaries | Minimum | Income taxes, net
Regulatory assets
Authorized amortization or recovery periods	1 year
Hawaiian Electric Company, Inc. and Subsidiaries | Minimum | Decoupling revenue balancing account
Regulatory assets
Authorized amortization or recovery periods	1 year
Hawaiian Electric Company, Inc. and Subsidiaries | Minimum | Unamortized expense and premiums on retired debt and equity issuances
Regulatory assets
Authorized amortization or recovery periods	19 years
Remaining amortization or recovery periods	6 years
Hawaiian Electric Company, Inc. and Subsidiaries | Minimum | Other, regulatory assets
Regulatory assets
Authorized amortization or recovery periods	1 year
Remaining amortization or recovery periods	1 year
Hawaiian Electric Company, Inc. and Subsidiaries | Maximum | Cost of removal in excess of salvage value
Regulatory liabilities
Authorized amortization or recovery periods	60 years
Hawaiian Electric Company, Inc. and Subsidiaries | Maximum | Other, regulatory liabilities
Regulatory liabilities
Remaining amortization or recovery periods	2 years
Hawaiian Electric Company, Inc. and Subsidiaries | Maximum | Income taxes, net
Regulatory assets
Authorized amortization or recovery periods	55 years
Hawaiian Electric Company, Inc. and Subsidiaries | Maximum | Decoupling revenue balancing account
Regulatory assets
Authorized amortization or recovery periods	2 years
Hawaiian Electric Company, Inc. and Subsidiaries | Maximum | Unamortized expense and premiums on retired debt and equity issuances
Regulatory assets
Authorized amortization or recovery periods	30 years
Remaining amortization or recovery periods	18 years
Hawaiian Electric Company, Inc. and Subsidiaries | Maximum | Other, regulatory assets
Regulatory assets
Authorized amortization or recovery periods	50 years
Remaining amortization or recovery periods	46 years
Hawaiian Electric Company, Inc. and Subsidiaries | Current assets
Regulatory assets
Regulatory assets	$ 72,231	71,421
Hawaiian Electric Company, Inc. and Subsidiaries | Long-term assets
Regulatory assets
Regulatory assets	824,500	833,843
Hawaiian Electric Company, Inc. and Subsidiaries | Current liabilities
Regulatory liabilities
Regulatory liabilities	2,204	632
Hawaiian Electric Company, Inc. and Subsidiaries | Long-term liabilities
Regulatory liabilities
Regulatory liabilities	$ 369,339	$ 344,217