Percentage of profit after capital investment and interest is returned

No definition available.

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- Definition

Percentage of profit until capital investment and interest is returned

+ References

No definition available.

+ Details

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Namespace Prefix:	hnrg_
Data Type:	num:percentItemType
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Period Type:	instant

- Definition

Date when the business acquisition agreement was executed, in CCYY-MM-DD format.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:dateItemType
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Period Type:	duration

- Definition

Line items represent financial concepts included in a table. These concepts are used to disclose reportable information associated with domain members defined in one or many axes to the table.

+ References

No definition available.

+ Details

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- Definition

Amount of consideration transferred, consisting of acquisition-date fair value of assets transferred by the acquirer, liabilities incurred by the acquirer, and equity interest issued by the acquirer.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 7
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6578-128477

Reference 2: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 50
-Paragraph 1
-Subparagraph (b)
-URI http://asc.fasb.org/extlink&oid=35744584&loc=d3e6927-128479

Reference 3: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 805
-SubTopic 30
-Section 30
-Paragraph 8
-URI http://asc.fasb.org/extlink&oid=6911251&loc=d3e6613-128477

+ Details

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- Definition

This element represents the total consolidated (as applicable) capitalization of the entity which is comprised of its long-term debt and equity instruments. The table may be detailed by subsidiary (legal entity) and include information by type of debt or equity detailed by instrument.

+ References

No definition available.

+ Details

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Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	instant

- Definition

Cost incurred related to exploration, development, mining, processing and providing mining support activities related to coal.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 225
-SubTopic 10
-Section S99
-Paragraph 2
-Subparagraph (SX 210.5-03.2(a),(d))
-URI http://asc.fasb.org/extlink&oid=63488584&loc=d3e20235-122688

+ Details

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Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration

- Definition

The percentage of ownership of common stock or equity participation in the investee accounted for under the equity method of accounting.

+ References

Reference 1: http://www.xbrl.org/2003/role/presentationRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 323
-SubTopic 10
-Section 50
-Paragraph 3
-Subparagraph (a)(1)
-URI http://asc.fasb.org/extlink&oid=66011266&loc=d3e33918-111571

+ Details

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- Details

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- Details

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- Details

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- Details

Name:	us-gaap_BusinessAcquisitionAxis=hnrg_HourglassSandsLlcMember
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Hourglass Sands (Narrative) (Details) - USD ($)	1 Months Ended	3 Months Ended		6 Months Ended
Hourglass Sands (Narrative) (Details) - USD ($)	Feb. 28, 2018	Jun. 30, 2018	Jun. 30, 2017	Jun. 30, 2018	Jun. 30, 2017
Business Acquisition [Line Items]
Operating costs and expenses		$ 38,874,000	$ 44,079,000	$ 85,514,000	$ 83,771,000
Hourglass [Member]
Business Acquisition [Line Items]
Percentage of profit after capital investment and interest is returned		90.00%		90.00%
Capitalization		$ 8,000,000		$ 8,000,000
Hourglass [Member] \| Director [Member]
Business Acquisition [Line Items]
Business acquisition purchase price	$ 4,000,000
Capital Unit, Class A [Member] \| Hourglass [Member]
Business Acquisition [Line Items]
Percentage of profit until capital investment and interest is returned		100.00%		100.00%
Hourglass Sands, LLC [Member]
Business Acquisition [Line Items]
Date of acquisition agreement				Feb. 01, 2018
Business acquisition purchase price	$ 4,000,000
Operating costs and expenses				$ 557,000
Hourglass Sands, LLC [Member] \| Hourglass [Member] \| Director [Member]
Business Acquisition [Line Items]
Date of acquisition agreement				Feb. 01, 2018
Hourglass Sands, LLC [Member] \| Capital Unit, Class A [Member] \| Hourglass [Member]
Business Acquisition [Line Items]
Equity method investment ownership percentage		100.00%		100.00%