Unconsolidated variable interest entities (Details) - HECO (USD $)	3 Months Ended		6 Months Ended			3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended		3 Months Ended		6 Months Ended						1 Months Ended	6 Months Ended			6 Months Ended
	Jun. 30, 2013	Jun. 30, 2012	Jun. 30, 2013	Jun. 30, 2012	Dec. 31, 2012	Jun. 30, 2013 Hawaiian Electric Company, Inc. and Subsidiaries entity	Jun. 30, 2012 Hawaiian Electric Company, Inc. and Subsidiaries	Jun. 30, 2013 Hawaiian Electric Company, Inc. and Subsidiaries item kW entity	Jun. 30, 2012 Hawaiian Electric Company, Inc. and Subsidiaries	Jun. 30, 2013 Hawaiian Electric Company, Inc. and Subsidiaries AES Hawaii, Inc. (AES Hawaii)	Jun. 30, 2012 Hawaiian Electric Company, Inc. and Subsidiaries AES Hawaii, Inc. (AES Hawaii)	Jun. 30, 2013 Hawaiian Electric Company, Inc. and Subsidiaries AES Hawaii, Inc. (AES Hawaii)	Jun. 30, 2012 Hawaiian Electric Company, Inc. and Subsidiaries AES Hawaii, Inc. (AES Hawaii)	Jun. 30, 2013 Hawaiian Electric Company, Inc. and Subsidiaries Kalaeloa Partners, L.P. (Kalaeloa)	Jun. 30, 2012 Hawaiian Electric Company, Inc. and Subsidiaries Kalaeloa Partners, L.P. (Kalaeloa)	Jun. 30, 2013 Hawaiian Electric Company, Inc. and Subsidiaries Kalaeloa Partners, L.P. (Kalaeloa)	Jun. 30, 2012 Hawaiian Electric Company, Inc. and Subsidiaries Kalaeloa Partners, L.P. (Kalaeloa)	Jun. 30, 2013 Hawaiian Electric Company, Inc. and Subsidiaries Hamakua Energy Partners, L.P. (HEP)	Jun. 30, 2012 Hawaiian Electric Company, Inc. and Subsidiaries Hamakua Energy Partners, L.P. (HEP)	Jun. 30, 2013 Hawaiian Electric Company, Inc. and Subsidiaries Hamakua Energy Partners, L.P. (HEP)	Jun. 30, 2012 Hawaiian Electric Company, Inc. and Subsidiaries Hamakua Energy Partners, L.P. (HEP)	Jun. 30, 2013 Hawaiian Electric Company, Inc. and Subsidiaries HPOWER	Jun. 30, 2012 Hawaiian Electric Company, Inc. and Subsidiaries HPOWER	Jun. 30, 2013 Hawaiian Electric Company, Inc. and Subsidiaries HPOWER	Jun. 30, 2012 Hawaiian Electric Company, Inc. and Subsidiaries HPOWER	Jun. 30, 2013 Hawaiian Electric Company, Inc. and Subsidiaries Other IPPs	Jun. 30, 2012 Hawaiian Electric Company, Inc. and Subsidiaries Other IPPs	Jun. 30, 2013 Hawaiian Electric Company, Inc. and Subsidiaries Other IPPs	Jun. 30, 2012 Hawaiian Electric Company, Inc. and Subsidiaries Other IPPs	Jun. 30, 2013 Hawaii Electric Light Company, Inc. (HELCO)	Jun. 30, 2012 Hawaii Electric Light Company, Inc. (HELCO)	Jun. 30, 2013 Hawaii Electric Light Company, Inc. (HELCO)	Jun. 30, 2012 Hawaii Electric Light Company, Inc. (HELCO)	Jun. 30, 2013 Maui Electric Company, Limited (MECO)	Jun. 30, 2012 Maui Electric Company, Limited (MECO)	Jun. 30, 2013 Maui Electric Company, Limited (MECO)	Jun. 30, 2012 Maui Electric Company, Limited (MECO)	Jun. 30, 2013 HECO Capital Trust III	Jun. 30, 2012 HECO Capital Trust III	Dec. 31, 2012 HECO Capital Trust III	Mar. 31, 2004 HECO Capital Trust III Hawaiian Electric Company, Inc. and Subsidiaries	Mar. 31, 2004 HECO Capital Trust III Hawaiian Electric Company, Inc. and Subsidiaries 2004 Trust Preferred Securities item	Jun. 30, 2013 HECO Capital Trust III Hawaiian Electric Company, Inc. and Subsidiaries 2004 Trust Preferred Securities	Jun. 30, 2012 HECO Capital Trust III Hawaiian Electric Company, Inc. and Subsidiaries 2004 Trust Preferred Securities	Dec. 31, 2012 HECO Capital Trust III Hawaiian Electric Company, Inc. and Subsidiaries 2004 Trust Preferred Securities	Jun. 30, 2013 HECO Capital Trust III Hawaiian Electric Company, Inc. and Subsidiaries Trust Common Securities	Jun. 30, 2012 HECO Capital Trust III Hawaiian Electric Company, Inc. and Subsidiaries Trust Common Securities	Dec. 31, 2012 HECO Capital Trust III Hawaiian Electric Company, Inc. and Subsidiaries Trust Common Securities	Mar. 31, 2004 HECO Capital Trust III Hawaiian Electric Company, Inc. and Subsidiaries Trust Common Securities	Mar. 31, 2004 HECO Capital Trust III Hawaii Electric Light Company, Inc. (HELCO)	Mar. 31, 2004 HECO Capital Trust III Maui Electric Company, Limited (MECO)
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	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																																						1,700,000	1,700,000
Dividend distributions on Trust Preferred Securities																																											1,600,000	1,600,000
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								91.00%
Purchases from IPPs	178,000,000	188,000,000	332,000,000	353,000,000		135,271,000	141,136,000	246,426,000	265,916,000	37,000,000	37,000,000	60,000,000	72,000,000	79,000,000	83,000,000	143,000,000	152,000,000	9,000,000	15,000,000	20,000,000	29,000,000	12,000,000	15,000,000	27,000,000	31,000,000	41,000,000	38,000,000	82,000,000	69,000,000	29,278,000	37,395,000	59,400,000	71,303,000	13,895,000	9,821,000	25,982,000	15,922,000
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
Accounts payable	$ 175,038,000		$ 175,038,000		$ 212,379,000									$ 23,000,000		$ 23,000,000