General Business (Narrative) (Details) - USD ($) $ / shares in Units, $ in Thousands		3 Months Ended
	Apr. 15, 2019	Mar. 31, 2019	Mar. 31, 2018	Jan. 01, 2019
Revenue, Major Customer [Line Items]
DD&A		$ 11,738	$ 10,829
Revenue		89,313	$ 66,864
Right-of-use asset		426
Operating lease liabilities		$ 426
Subsequent Event [Member]
Revenue, Major Customer [Line Items]
Dividends payable, amount per share	$ 0.04
Dividends payable, date of record	Apr. 30, 2019
Dividends payable, date to be paid	May 17, 2019
Sunrise Energy [Member]
Revenue, Major Customer [Line Items]
Equity method investment ownership percentage		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