Proposed Merger (Details)				1 Months Ended		10 Months Ended
	Aug. 31, 2015 USD ($)	Aug. 10, 2015 USD ($)	Dec. 03, 2014 USD ($) $ / shares shares	Jul. 31, 2015 intervener	Jan. 31, 2015 USD ($)	Sep. 30, 2015 complaint	Apr. 30, 2015 action
Business Acquisition [Line Items]
Number of purported class action complaints filed | complaint						8
In re Consolidated HEI Shareholder Cases
Business Acquisition [Line Items]
Consolidated number of state actions | action							7
NextEra Energy, Inc Merger
Business Acquisition [Line Items]
Merger share conversion ratio | shares			0.2413
Minimum percentage of shares from which holders approval needed for merger			75.00%
Merger agreement contract extension			6 months
Merger contract termination fee			$ 90,000,000
Maximum expenses paid to party for cancellation of merger			$ 5,000,000
Minimum period that entity agrees not to submit applications for general base rate increase					4 years
Approximate amount of cumulative savings for customers due to forgone recoveries					$ 60,000,000
Number of interveners | intervener				28
Number of interveners who opposed | intervener				11
Number of interveners opposed who approved conditionally | intervener				11
Number of interveners who made no recommendation | intervener				6
Consumer advocate recommendation, permanent reduction in annual utility rate, amount		$ 62,000,000
Non-fuel O&M savings requirements	100.00%
Fund for public interest	$ 2,500,000
Corporate giving minimum	$ 2,200,000
Years post-closing for corporate giving minimum	10 years
Years post-closing for commitment not to sell utilities or holding company	10 years
NextEra Energy, Inc Merger | Hawaiian Electric Company, Inc. and Subsidiaries
Business Acquisition [Line Items]
Special dividend | $ / shares			$ 0.50