Unconsolidated variable interest entities (Details)	1 Months Ended						12 Months Ended
	Nov. 30, 2015 MW	Oct. 31, 2015 MW	Oct. 31, 2004 MW	Mar. 31, 2004 USD ($) security	May. 31, 1991 MW	Mar. 31, 1988 MW	Dec. 31, 2015 USD ($) entity agreement MW	Dec. 31, 2014 USD ($)	Dec. 31, 2013 USD ($)
Power purchase agreement
Number of power purchase agreements (PPAs) | agreement							5
Accounts payable							$ 138,523,000	$ 186,425,000
Hawaiian Electric Company, Inc. and Subsidiaries
Power purchase agreement
Purchases from IPPs							594,096,000	722,008,000	$ 710,681,000
Hawaiian Electric Company, Inc. and Subsidiaries | AES Hawaii, Inc. (AES Hawaii)
Power purchase agreement
Purchases from IPPs							134,000,000	145,000,000	134,000,000
Hawaiian Electric Company, Inc. and Subsidiaries | Kalaeloa Partners, L.P. (Kalaeloa)
Power purchase agreement
Purchases from IPPs							187,000,000	279,000,000	301,000,000
Hawaiian Electric Company, Inc. and Subsidiaries | Hamakua Energy Partners, L.P. (HEP)
Power purchase agreement
Purchases from IPPs							44,000,000	51,000,000	51,000,000
Hawaiian Electric Company, Inc. and Subsidiaries | HPOWER
Power purchase agreement
Purchases from IPPs							66,000,000	66,000,000	61,000,000
Hawaiian Electric Company, Inc. and Subsidiaries | Puna Geothermal Venture [Member]
Power purchase agreement
Purchases from IPPs							29,000,000	45,000,000	49,000,000
Hawaiian Electric Company, Inc. and Subsidiaries | Hawaiian Commercial & Sugar (HC&S) [Member]
Power purchase agreement
Purchases from IPPs							8,000,000	15,000,000	13,000,000
Hawaiian Electric Company, Inc. and Subsidiaries | Other IPPs
Power purchase agreement
Purchases from IPPs							$ 126,000,000	121,000,000	102,000,000
HECO
Power purchase agreement
Number of power purchase agreements (PPAs) | agreement							5
Maximum capacity of small power production facilities (in megawatts) | MW							0.1
Percentage of power purchase from AES Hawaii, Inc. (AES Hawaii), Kalaeloa Partners, L.P. (Kalaeloa), Hamakua Energy Partners, L.P. (HEP) and HPOWER							90.00%
Purchases from IPPs							$ 440,983,000	537,821,000	527,839,000
Number of entities owning wind farms not required to be consolidated as VIE's | entity							2
Minimum potential number of IPP entities consolidated into company in the future | entity							1
HECO | AES Hawaii, Inc. (AES Hawaii)
Power purchase agreement
Power purchase capacity (in megawatts) | MW	189					180
Number of years entity entered under power purchase agreement						30 years
Accounts payable							$ 12,000,000
HECO | Kalaeloa Partners, L.P. (Kalaeloa)
Power purchase agreement
Power purchase capacity (in megawatts) | MW					180
Number of years entity entered under power purchase agreement							25 years
Power purchase capacity that Increases from initial capacity (in megawatts) | MW			208
Power purchase agreement, termination period			60 days
Accounts payable							$ 11,000,000
Hawaii Electric Light Company, Inc. (HELCO)
Power purchase agreement
Purchases from IPPs							97,503,000	123,226,000	128,368,000
Maui Electric Company, Limited (MECO)
Power purchase agreement
Purchases from IPPs							$ 55,610,000	$ 60,961,000	$ 54,474,000
Maximum monthly scheduled energy (in megawatts) | MW		4
Maximum emergency power (in megawatts) | MW		16
HECO Capital Trust III
Unconsolidated variable interest entities
Variable interest entity, ownership percentage							100.00%
Investment in 2004 Debentures							$ 51,500,000
Interest income							3,400,000
HECO Capital Trust III | HECO
Unconsolidated variable interest entities
Principal amount of 2004 Debentures				$ 31,500,000
HECO Capital Trust III | HECO | 2004 Trust Preferred Securities
Unconsolidated variable interest entities
Number of 2004 Trust Preferred Securities issued | security				2,000,000
Dividend rate on 2004 Trust Preferred Securities (as a percent)				6.50%
Aggregate Liquidation preference				$ 50,000,000
Balance of Trust Securities							50,000,000
Dividend distributions on Trust Preferred Securities							3,300,000
HECO Capital Trust III | HECO | Trust Common Securities
Unconsolidated variable interest entities
Aggregate Liquidation preference				1,500,000
Balance of Trust Securities							1,500,000
Common dividend							$ 100,000
HECO Capital Trust III | Hawaii Electric Light Company, Inc. (HELCO)
Unconsolidated variable interest entities
Principal amount of 2004 Debentures				10,000,000
HECO Capital Trust III | Maui Electric Company, Limited (MECO)
Unconsolidated variable interest entities
Principal amount of 2004 Debentures				$ 10,000,000