Supplemental Financial Data - Oil and Gas Producing Activities (unaudited) (Details 2) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017
Property acquisition costs:
Unevaluated properties	$ 3,464	$ 1
Proved properties and gathering facilities	63,517	289
Development costs	2,074	952
Gathering facilities	460	43
Asset retirement obligation	14,085	2,309
Total costs incurred	$ 83,600	$ 3,594