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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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Dividends declared in the period and the contractual amount of dividends (or interest on participating income bonds) that must be paid per security.

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Earnings per share and shareholders' equity (Details) (USD $) In Millions, except Share data, unless otherwise specified	3 Months Ended
	Mar. 31, 2013	Mar. 31, 2012	Mar. 20, 2013	Mar. 19, 2013
Basic
Distributed earnings (in dollars per share)	$ 0.31	$ 0.31
Undistributed earnings (loss) (in dollars per share)	$ 0.03	$ 0.09
Earnings Per Share, basic (in dollars per share)	$ 0.34	$ 0.40
Diluted
Distributed earnings (in dollars per share)	$ 0.31	$ 0.31
Undistributed earnings (losses) (in dollars per share)	$ 0.03	$ 0.09
Earnings Per Share, diluted (in dollars per share)	$ 0.34	$ 0.40
Antidilutive effect of HEI common stock
Antidilutive effects of SARs shares that were not included in the computation of diluted EPS (in shares)	0	210,000
Equity forward transaction
Public offering related to equity forward transaction (in shares)				6,100,000
Offering related to underwriters exercising their over-allotment option under equity forward transaction (in shares)			900,000
Shares borrowed by forward counterparty from third party	7,000,000
Sale of common stock to underwriters (in dollars per share)	$ 26.75
Underwriting discount (in dollars per share)	$ 1.00312
Forward sale price (in dollars per share)	$ 25.74688
Initial fair value (in dollars per share)	$ 0
Cash in exchange of physical delivery of shares on settlement	$ 180
Delivery of cash on settlement	12
Underwriting discount included in delivery of cash	$ 7
Delivery of net shares on settlement	440,000