Property, Plant and Equipment - Cost of Assets Acquired (Details) $ in Thousands	Feb. 20, 2019 USD ($)
Cost of asset acquisition:
Cash	$ 79,100
Promissory note	1,500
Consideration transferred	80,600
Oil and gas properties	97,298
Net working capital (including cash acquired of $5.3 million)	(16,698)
Net assets acquired	80,600
Cash acquired	5,300
Proved
Cost of asset acquisition:
Oil and gas properties	52,530
Unproved
Cost of asset acquisition:
Oil and gas properties	$ 44,768