Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	6 Months Ended
	Jun. 30, 2019	Jun. 30, 2018
Supplemental Cash Flow Elements [Abstract]
Cash paid for interest	$ 182	$ 34
Cash paid for federal and state income taxes	233	210
Non-cash transactions:
Change in accounts payable related to property and equipment additions	(1,179)	(44)
Property and equipment acquired under finance leases	4,148	0
Issuance of common shares in asset acquisition (see Note 6)	$ 392	$ 0