Commitments (Details Textual)	Jun. 30, 2017 USD ($)
Commitments (Textual)
Liability related to firm transportation contracts assumed	$ 541,000
Capital commitment	240,000
Carbon Appalachia [Member]
Commitments (Textual)
Capital commitment	$ 2,000,000

Minimum amount of other commitment not otherwise specified in the taxonomy. Excludes commitments explicitly modeled in the taxonomy, including but not limited to, long-term and short-term purchase commitments, recorded and unrecorded purchase obligations, supply commitments, registration payment arrangements, leases, debt, product warranties, guarantees, environmental remediation obligations, and pensions.

No definition available.

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