(5) Other Long-Term Assets and Other Income (Detail) (USD $) In Millions, unless otherwise specified	9 Months Ended
Sep. 30, 2012	Sep. 30, 2011
MSHA Reimbursements footnote	$ 4.2	$ 1.9

Dollars reimbursed by purchasers for government mandated compliance regulations

No definition available.

Name:	hnrg_MSHAReimbursementsApprox
Namespace Prefix:	hnrg_
Data Type:	xbrli:monetaryItemType
Balance Type:	credit
Period Type:	duration