Earnings per share (Details) (USD $)	3 Months Ended
Mar. 31, 2012	Mar. 31, 2011
Basic
Distributed earnings (in dollars per share)	$ 0.31	$ 0.31
Undistributed earnings (losses) (in dollars per share)	$ 0.09	$ (0.01)
Earnings Per Share, basic (in dollars per share)	$ 0.40	$ 0.30
Diluted
Distributed earnings (in dollars per share)	$ 0.31	$ 0.31
Undistributed earnings (losses) (in dollars per share)	$ 0.09	$ (0.01)
Earnings Per Share, diluted (in dollars per share)	$ 0.40	$ 0.30
Stock appreciation rights (SARs) \| Common stock.
Antidilutive effect of HEI common stock
Antidilutive effects of SARs shares that were not included in the computation of diluted EPS (in shares)	210,000	414,000

Securities (including those issuable pursuant to contingent stock agreements) that could potentially dilute basic earnings per share (EPS) or earnings per unit (EPU) in the future that were not included in the computation of diluted EPS or EPU because to do so would increase EPS or EPU amounts or decrease loss per share or unit amounts for the period presented.

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The amount of net income (loss) for the period per each share of common stock or unit outstanding during the reporting period.

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