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General Business (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended		9 Months Ended
	Oct. 15, 2019	Sep. 30, 2019	Sep. 30, 2018	Sep. 30, 2019	Sep. 30, 2018	Jan. 01, 2019
Revenue, Major Customer [Line Items]
DD&A		$ 11,778	$ 10,815	$ 35,612	$ 32,764
Revenue		83,096	$ 79,722	244,719	$ 203,829
Right-of-use asset		882		882
Operating lease liabilities		$ 882		$ 882
Subsequent Event [Member]
Revenue, Major Customer [Line Items]
Dividends payable, amount per share	$ 0.04
Dividends payable, date of record	Oct. 31, 2019
Dividends payable, date to be paid	Nov. 15, 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