Credit agreement and long-term debt (Details) (USD $)	3 Months Ended								0 Months Ended
	Mar. 31, 2014	Mar. 31, 2013	Mar. 31, 2014 Maximum	Mar. 31, 2014 HELCO	Mar. 31, 2014 Maui Electric	Mar. 31, 2014 Line of credit facility	Mar. 31, 2014 Line of credit facility Hawaiian Electric Company	Apr. 02, 2014 Subsequent Event Institution	Apr. 02, 2014 Subsequent Event Line of credit facility	Apr. 02, 2014 Subsequent Event Line of credit facility Hawaiian Electric Company	May 02, 2014 Eurodollar term loan Subsequent Event Loans payable	May 05, 2014 Medium-term Notes 6.51 Percent Due 2014 Subsequent Event Medium-term note	Apr. 02, 2014 Adjusted LIBO Rate Subsequent Event Line of credit facility	Apr. 02, 2014 Adjusted LIBO Rate Subsequent Event Line of credit facility Hawaiian Electric Company
Credit agreement
Number of financial institutions								9
Revolving noncollateralized credit facility with a letter of credit sub-facility						$ 125,000,000	$ 175,000,000		$ 150,000,000	$ 200,000,000
Basis spread on variable rate													1.375%	1.25%
Unused capacity commitment fee									0.20%	0.175%
Capitalization ratio required to be maintained as per the debt covenant (as a percent)			50.00%
Actual capitalization ratio (as a percent)	18.00%
Ratio of consolidated subsidiary debt to total consolidated capitalization required to be maintained as per the debt covenant (as a percent)	65.00%
Actual ratio of consolidated subsidiary debt to total consolidated capitalization (as a percent)				42.00%	45.00%
Ratio of consolidated capitalization required to be maintained as per the debt covenant (as a percent)	35.00%
Actual ratio of consolidated debt to total consolidated capitalization (as a percent)	56.00%
Changes in long-term debt
Long-term debt	0	50,000,000									125,000,000
Term of loan											2 years
Initial interest rate for initial period											1.12%
Initial interest period											3 months
Repayments of debt												$ 100,000,000
Debt instrument, stated interest rate (as a percent)												6.51%