XML 31 R15.htm IDEA: XBRL DOCUMENT
v3.3.1.900

Self Insurance | 12 Months Ended
--- | ---
Dec. 31, 2015
Self Insurance [Abstract] |
Self Insurance | (9) Self Insurance In late August 2010 we decided to terminate the property insurance on our underground mining equipment. Such equipment is allocated among 10 mining units spread out over 20 miles. The historical cost of such equipment is about $250 million.

X
- Definition Self Insurance + References No definition available. + Details
Name: | hnrg_SelfInsurance
Namespace Prefix: | hnrg_
Data Type: | nonnum:textBlockItemType
Balance Type: | na
Period Type: | duration

X
- References No definition available. + Details
Name: | hnrg_SelfInsuranceAbstract
Namespace Prefix: | hnrg_
Data Type: | xbrli:stringItemType
Balance Type: | na
Period Type: | duration