Summary of Significant Accounting Policies (Details) $ in Thousands	6 Months Ended	12 Months Ended
Jun. 30, 2019 USD ($) Partnerships	Dec. 31, 2018
Accounting Policies [Abstract]
Insurance settlement received \| $	$ 800
Number of consolidated partnerships \| Partnerships	46
Carbon Appalachia [Member]
Accounting Policies [Abstract]
Percentage of ownership interest in the subsidiary		100.00%
Nytis LLC [Member] \| Nytis USA [Member]
Accounting Policies [Abstract]
Percentage of ownership interest in the subsidiary		98.10%
Nytis USA [Member]
Accounting Policies [Abstract]
Percentage of ownership interest in the subsidiary		100.00%

Amount of cash inflow for proceeds from settlement of insurance claim, classified as investing activities. Excludes insurance settlement classified as operating activities.

Reference 1: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 21B
-URI http://asc.fasb.org/extlink&oid=118932676&loc=SL94080549-108585

Reference 2: http://fasb.org/us-gaap/role/ref/legacyRef
-Publisher FASB
-Name Accounting Standards Codification
-Topic 230
-SubTopic 10
-Section 45
-Paragraph 12
-URI http://asc.fasb.org/extlink&oid=118932676&loc=d3e3179-108585

Name:	us-gaap_ProceedsFromInsuranceSettlementInvestingActivities
Namespace Prefix:	us-gaap_
Data Type:	xbrli:monetaryItemType
Balance Type:	debit
Period Type:	duration