Note 8 - Income Tax - Deferred Tax Assets and Liabilities (Details) - USD ($) $ in Thousands	Dec. 31, 2019	Dec. 31, 2018
Deferred tax liabilities:
Amortization	$ (11,133)	$ (10,947)
Depreciation	(10,934)	(9,978)
Lease asset	(306)
Prepaid expense	(506)	(357)
Other	(8)	(8)
Total deferred tax liabilities	(22,887)	(21,290)
Deferred tax assets:
Deferred compensation	147	142
Advance payments	597	612
Lease liability	306
Bad debt	77	145
Other	239	246
Total deferred tax assets	$ 1,366	$ 1,145