Electric utility subsidiary - Unconsolidated variable interest entities (Details) (USD $)	3 Months Ended		9 Months Ended			3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended		3 Months Ended		9 Months Ended						1 Months Ended	9 Months Ended			9 Months Ended
	Sep. 30, 2014	Sep. 30, 2013	Sep. 30, 2014	Sep. 30, 2013	Dec. 31, 2013	Sep. 30, 2014 Hawaiian Electric Company entity	Sep. 30, 2013 Hawaiian Electric Company	Sep. 30, 2014 Hawaiian Electric Company kW agreement entity	Sep. 30, 2013 Hawaiian Electric Company	Sep. 30, 2014 Hawaiian Electric Company AES Hawaii, Inc. (AES Hawaii)	Sep. 30, 2013 Hawaiian Electric Company AES Hawaii, Inc. (AES Hawaii)	Sep. 30, 2014 Hawaiian Electric Company AES Hawaii, Inc. (AES Hawaii)	Sep. 30, 2013 Hawaiian Electric Company AES Hawaii, Inc. (AES Hawaii)	Sep. 30, 2014 Hawaiian Electric Company Kalaeloa Partners, L.P. (Kalaeloa)	Sep. 30, 2013 Hawaiian Electric Company Kalaeloa Partners, L.P. (Kalaeloa)	Sep. 30, 2014 Hawaiian Electric Company Kalaeloa Partners, L.P. (Kalaeloa) MW	Sep. 30, 2013 Hawaiian Electric Company Kalaeloa Partners, L.P. (Kalaeloa)	Sep. 30, 2014 Hawaiian Electric Company Hamakua Energy Partners, L.P. (HEP)	Sep. 30, 2013 Hawaiian Electric Company Hamakua Energy Partners, L.P. (HEP)	Sep. 30, 2014 Hawaiian Electric Company Hamakua Energy Partners, L.P. (HEP)	Sep. 30, 2013 Hawaiian Electric Company Hamakua Energy Partners, L.P. (HEP)	Sep. 30, 2014 Hawaiian Electric Company HPOWER	Sep. 30, 2013 Hawaiian Electric Company HPOWER	Sep. 30, 2014 Hawaiian Electric Company HPOWER	Sep. 30, 2013 Hawaiian Electric Company HPOWER	Sep. 30, 2014 Hawaiian Electric Company Other IPPs	Sep. 30, 2013 Hawaiian Electric Company Other IPPs	Sep. 30, 2014 Hawaiian Electric Company Other IPPs	Sep. 30, 2013 Hawaiian Electric Company Other IPPs	Sep. 30, 2014 Hawaii Electric Light Company, Inc. (HELCO)	Sep. 30, 2013 Hawaii Electric Light Company, Inc. (HELCO)	Sep. 30, 2014 Hawaii Electric Light Company, Inc. (HELCO)	Sep. 30, 2013 Hawaii Electric Light Company, Inc. (HELCO)	Sep. 30, 2014 Maui Electric Company (MECO)	Sep. 30, 2013 Maui Electric Company (MECO)	Sep. 30, 2014 Maui Electric Company (MECO)	Sep. 30, 2013 Maui Electric Company (MECO)	Sep. 30, 2014 HECO Capital Trust III	Sep. 30, 2013 HECO Capital Trust III	Dec. 31, 2013 HECO Capital Trust III	Mar. 31, 2004 HECO Capital Trust III Hawaiian Electric Company	Mar. 31, 2004 HECO Capital Trust III Hawaiian Electric Company 2004 Trust Preferred Securities security	Sep. 30, 2014 HECO Capital Trust III Hawaiian Electric Company 2004 Trust Preferred Securities	Sep. 30, 2013 HECO Capital Trust III Hawaiian Electric Company 2004 Trust Preferred Securities	Dec. 31, 2013 HECO Capital Trust III Hawaiian Electric Company 2004 Trust Preferred Securities	Sep. 30, 2014 HECO Capital Trust III Hawaiian Electric Company Trust Common Securities	Sep. 30, 2013 HECO Capital Trust III Hawaiian Electric Company Trust Common Securities	Dec. 31, 2013 HECO Capital Trust III Hawaiian Electric Company Trust Common Securities	Mar. 31, 2004 HECO Capital Trust III Hawaiian Electric Company Trust Common Securities	Mar. 31, 2004 HECO Capital Trust III Hawaii Electric Light Company, Inc. (HELCO)
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							$ 1,500,000
Principal amount of 2004 Debentures																																									31,500,000									10,000,000
Investment in 2004 Debentures																																						51,500,000		51,500,000
Balance of Trust Securities																																											50,000,000		50,000,000	1,500,000		1,500,000
Interest income																																						2,500,000	2,500,000
Dividend distributions on Trust Preferred Securities																																											2,400,000	2,400,000
Common dividend																																														100,000	100,000
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		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	193,000,000	195,000,000	546,000,000	527,000,000		142,121,000	143,280,000	406,895,000	389,706,000	38,000,000	38,000,000	107,000,000	98,000,000	73,000,000	80,000,000	214,000,000	223,000,000	16,000,000	15,000,000	36,000,000	36,000,000	18,000,000	17,000,000	50,000,000	44,000,000	48,000,000	45,000,000	139,000,000	126,000,000	34,166,000	34,480,000	91,827,000	93,880,000	16,595,000	17,101,000	47,399,000	43,083,000
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
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	$ 177,495,000		$ 177,495,000		$ 212,331,000									$ 16,000,000		$ 16,000,000