Supplemental Cash Flow Information (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Supplemental Cash Flow Elements [Abstract]
Cash paid for interest	$ 444	$ 636	$ 109
Cash paid for federal and state income taxes	418	234	787
Cash refund for NOL carryback under CARES Act	2,703	0	0
Non-cash transactions:
Change in accounts payable related to property and equipment	(1,237)	(448)	1,685
Property and equipment acquired under capital leases	11,412	4,148	2,898
Issuance of common shares in asset acquisition (see Note 6)	0	392	0
Receivable for sale of property and equipment	$ 0	$ 952	$ 0