Note 8 - Income Tax - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2018	Dec. 31, 2017
Deferred tax liabilities:
Amortization	$ (10,947)	$ (11,058)
Depreciation	(9,701)	(8,408)
Prepaid expense	(357)	(151)
State net operating loss carryforwards and adjustments, liabilties	(277)	(266)
Other	(8)	(8)
Total deferred tax liabilities	(21,290)	(19,891)
Deferred tax assets:
Deferred compensation	142	131
Advance payments	612	520
Bad debt	145	71
Other	246	230
Total deferred tax assets	$ 1,145	$ 952