Earnings per share and shareholders' equity (Details 2) (USD $) In Thousands, unless otherwise specified	3 Months Ended
Mar. 31, 2015	Mar. 31, 2014
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Beginning balance	$ (27,378)	$ (16,750)
Current period other comprehensive income	4,058	1,167
Ending balance	(23,320)	(15,583)
Net unrealized gains (losses) on securities
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Beginning balance	462	(3,663)
Current period other comprehensive income	3,451	805
Ending balance	3,913	(2,858)
Unrealized losses on derivatives
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Beginning balance	(289)	(525)
Current period other comprehensive income	59	59
Ending balance	(230)	(466)
Retirement benefit plans
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Beginning balance	(27,551)	(12,562)
Current period other comprehensive income	548	303
Ending balance	(27,003)	(12,259)
Hawaiian Electric Company, Inc. and Subsidiaries \| Retirement benefit plans
Reclassification from Accumulated Other Comprehensive Income, Current Period, Net of Tax [Abstract]
Beginning balance	45	608
Current period other comprehensive income	22	9
Ending balance	$ 67	$ 617

- Definition

Accumulated change in equity from transactions and other events and circumstances from non-owner sources, net of tax effect, at period end. Excludes Net Income (Loss), and accumulated changes in equity from transactions resulting from investments by owners and distributions to owners. Includes foreign currency translation items, certain pension adjustments, unrealized gains and losses on certain investments in debt and equity securities, other than temporary impairment (OTTI) losses related to factors other than credit losses on available-for-sale and held-to-maturity debt securities that an entity does not intend to sell and it is not more likely than not that the entity will be required to sell before recovery of the amortized cost basis, as well as changes in the fair value of derivatives related to the effective portion of a designated cash flow hedge.

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