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General Business (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		6 Months Ended
	Jul. 16, 2019	Jun. 30, 2019	Jun. 30, 2018	Jun. 30, 2019	Jun. 30, 2018	Jan. 01, 2019
Revenue, Major Customer [Line Items]
DD&A		$ 12,096	$ 11,120	$ 23,834	$ 21,949
Revenue		72,310	$ 57,243	161,623	$ 124,107
Right-of-use asset		942		942
Operating lease liabilities		$ 942		$ 942
Subsequent Event [Member]
Revenue, Major Customer [Line Items]
Dividends payable, amount per share	$ 0.04
Dividends payable, date of record	Jul. 31, 2019
Dividends payable, date to be paid	Aug. 16, 2019
Sunrise Energy [Member]
Revenue, Major Customer [Line Items]
Equity method investment ownership percentage		50.00%		50.00%
Restatement Adjustment [Member] \| Accounting Standards Update 2016-02 [Member]
Revenue, Major Customer [Line Items]
Right-of-use asset						$ 500
Operating lease liabilities						$ 500