Note 16 - Income Tax (Benefit) Provision - Components of Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Compensation	$ 267	$ 30
Inventory reserves	650	458
Self-insurance	103	63
Asset retirement obligation	199	209
Deferred revenue	4,427	5,015
Federal net operating loss carryforwards	3,121	1
State net operating loss carryforwards	363
Accrued expenses	1,684	1,653
Stock-based compensation	41	108
State credit carryforwards	343
Derivative instruments	56
Other		130
Total deferred tax assets	11,254	7,667
Available-for-sale securities, unrealized gains	(79)
Derivative instruments		(86)
LIFO inventory	(2,860)	(3,389)
Depreciation	(19,891)	(22,010)
Marketable securities, unrealized gains	(1,334)
Other	(55)	(208)
Total deferred tax liabilities	(24,219)	(25,693)
Net deferred tax liabilities	$ (12,965)	$ (18,026)