Income Taxes (Expected Income Tax) (Details) (USD $) In Thousands, unless otherwise specified	12 Months Ended
Dec. 31, 2014	Dec. 31, 2013
Income Taxes [Abstract]
Expected amount	$ 3,745hnrg_TaxExpectedAmount	$ 10,359hnrg_TaxExpectedAmount
Change in Indiana rate	(1,407)
State income taxes, net of federal benefit	186	877
Percentage depletion	(1,996)	(3,826)
Stock-based compensation	343
Captive insurance	(419)	(419)
Other	30hnrg_TaxExpectedOther	184hnrg_TaxExpectedOther
Total tax expected	$ 482hnrg_TotalTaxExpected	$ 7,175hnrg_TotalTaxExpected

Expected State Income Taxes Net Of Federal Benefit

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Tax Expected Amount

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Total Tax Expected

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations, attributable to increase (decrease) in the income tax rates.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef

-Publisher FASB

-Name Accounting Standards Codification

-Topic 740

-SubTopic 10

-Section 50

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-Name Accounting Standards Codification

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-URI http://asc.fasb.org/extlink&oid=6907707&loc=d3e32698-109319

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-Name Accounting Standards Codification

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-Section 45

-Paragraph 15

-URI http://asc.fasb.org/extlink&oid=21917399&loc=d3e32059-109318

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Amount of the difference between reported income tax expense (benefit) and expected income tax expense (benefit) computed by applying the domestic federal statutory income tax rates to pretax income (loss) from continuing operations attributable to nondeductible equity-based compensation costs.

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