Credit agreement - HECO Credit agreement - (Details1) - HECO (USD $)	0 Months Ended				0 Months Ended																				1 Months Ended
	Oct. 03, 2013	Sep. 30, 2013 Senior Notes Refunding Series 2003 A Due 2020 Debt 4.75 Percent	Sep. 30, 2013 Senior Notes Refunding Series 2003 B Due 2022 Debt 5 Percent	Sep. 30, 2013 Senior Notes Refunding Series 1997A Bonds	Oct. 03, 2013 Subsequent Event Senior Notes contract	Oct. 03, 2013 Subsequent Event Senior Notes Hawaiian Electric Notes, Senior Notes	Oct. 03, 2013 Subsequent Event Senior Notes Senior Notes, Series 2013A		Oct. 03, 2013 Subsequent Event Senior Notes Senior Notes, Series 2013B		Oct. 03, 2013 Subsequent Event Senior Notes Senior Notes, Series 2013C		Oct. 03, 2013 Subsequent Event Senior Notes Maui Electric Notes, Senior Notes	Oct. 03, 2013 Subsequent Event Senior Notes Senior Notes, Series 2013A		Oct. 03, 2013 Subsequent Event Senior Notes Senior Notes, Series 2013B		Oct. 03, 2013 Subsequent Event Senior Notes Hawaii Electric Light Notes, Senior Notes	Oct. 03, 2013 Subsequent Event Senior Notes Senior Notes, Series 2013A		Oct. 03, 2013 Subsequent Event Senior Notes Senior Notes, Series 2013B		Oct. 03, 2013 Subsequent Event Senior Notes Senior Notes, Series 2013C		Oct. 31, 2013 Subsequent Event Special Purpose Revenue Bonds
Debt Instrument [Line Items]
Bonds redeemed																									$ 166,000,000
Senior notes, face amount					$ 236,000,000	$ 140,000,000	$ 40,000,000	[1]	$ 50,000,000	[1]	$ 50,000,000	[2]	$ 40,000,000	$ 20,000,000	[1]	$ 20,000,000	[2]	$ 56,000,000	$ 14,000,000	[1]	$ 12,000,000	[1]	$ 30,000,000	[1]
Debt instrument, stated interest rate (as a percent)		4.75%	5.00%	5.65%			4.45%	[1]	4.84%	[1]	5.65%	[2]		4.84%	[1]	5.65%	[2]		3.83%	[1]	4.45%	[1]	4.84%	[1]
Debt Instrument, Number Of Purchase Agreements					3
Debt Instrument, Covenant Terms, Contingent Prepayment Required, Minimum Ownership Percentage Required					100.00%
Debt Instrument, Covenant Terms, Investment Grade Rating Required To Avoid Affiliate Prepayment Offer, Term	90 days

[1] Proceeds were used in October 2013 to redeem the following special purpose revenue bonds (SPRBs) and refunding SPRBs issued by the Department of Budget and Finance of the State of Hawaii for the benefit of the Utilities with an aggregate principle amount of $166 million:

[2] Proceeds were and/or will be used by the respective utility to finance their capital expenditures and/or for the reimbursement of funds used for the payment of capital expenditures.