Electric utility subsidiary - Unconsolidated variable interest entities (Details) (USD $)	1 Months Ended	3 Months Ended
	Mar. 31, 2004 security	Mar. 31, 2014	Mar. 31, 2013	Dec. 31, 2013
Power purchase agreement
Purchases from IPPs		$ 165,000,000	$ 153,000,000
Accounts payable		210,511,000		212,331,000
Hawaiian Electric Company
Power purchase agreement
Number of power purchase agreements (PPAs)		6
Maximum capacity of small power production facilities (in kilowatts)		100
Number of entities currently not required to be consolidated as VIEs		0
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%
Variable Interest Entity, Unavailability of Information, Number of Entities		3
Purchases from IPPs		123,969,000	111,155,000
Number of firm capacity producers declining to provide financial information to determine primary beneficiary status		2
Minimum potential number of IPP entities consolidated into company in the future		1
Hawaiian Electric Company | AES Hawaii, Inc. (AES Hawaii)
Power purchase agreement
Purchases from IPPs		33,000,000	23,000,000
Hawaiian Electric Company | Kalaeloa Partners, L.P. (Kalaeloa)
Power purchase agreement
Purchases from IPPs		67,000,000	65,000,000
Power purchase capacity that Increases from initial capacity (in megawatts)		180
Number of years entity entered under power purchase agreement		25 years
Power purchase capacity that Increases from initial capacity (in megawatts)		208
Accounts payable		23,000,000
Hawaiian Electric Company | Hamakua Energy Partners, L.P. (HEP)
Power purchase agreement
Purchases from IPPs		12,000,000	12,000,000
Hawaiian Electric Company | HPOWER
Power purchase agreement
Purchases from IPPs		16,000,000	15,000,000
Hawaiian Electric Company | Other IPPs
Power purchase agreement
Purchases from IPPs		37,000,000	38,000,000
Hawaii Electric Light Company, Inc. (HELCO)
Power purchase agreement
Purchases from IPPs		29,491,000	30,122,000
Maui Electric Company (MECO)
Power purchase agreement
Purchases from IPPs		11,456,000	12,087,000
HECO Capital Trust III
Unconsolidated variable interest entities
Investment in 2004 Debentures		51,500,000		51,500,000
Interest income		800,000	800,000
HECO Capital Trust III | Hawaiian Electric Company
Unconsolidated variable interest entities
Principal amount of 2004 Debentures	31,500,000
HECO Capital Trust III | Hawaiian Electric Company | 2004 Trust Preferred Securities
Unconsolidated variable interest entities
Number of 2004 Trust Preferred Securities issued	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		50,000,000
Dividend distributions on Trust Preferred Securities		800,000	800,000
HECO Capital Trust III | Hawaiian Electric Company | Trust Common Securities
Unconsolidated variable interest entities
Aggregate Liquidation preference	1,500,000
Balance of Trust Securities		1,500,000		1,500,000
Common dividend		25,000	25,000
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 (MECO)
Unconsolidated variable interest entities
Principal amount of 2004 Debentures	$ 10,000,000