Prepaid Expenses and Other Current Assets (Details) - USD ($) $ in Thousands	Jun. 30, 2018	Dec. 31, 2017
Prepaid Expenses and Other Current Assets
Rio Grande LNG site option	$ 794	$ 1,080
Short-term security deposits	367	364
Galveston Bay leases	250	100
Rio Bravo Pipeline options	82	111
Prepaid insurance	84	208
Prepaid marketing sponsorships	235	55
Deferred equity issuance costs	127
Other	256	181
Total prepaid expenses and other current assets	$ 2,195	$ 2,099