Note 17 - Income Taxes - Reconciliation Between U.S. Federal Statutory Rate and Effective Rate (Details)	12 Months Ended
	Dec. 31, 2020	Dec. 31, 2019	Dec. 31, 2018
Statutory federal income tax rate	21.00%	21.00%	21.00%
State tax expense, net of federal benefit	1.50%	5.50%	5.50%
Stock compensation and Section 162(m) limitation	(2.20%)	0.90%	(0.50%)
Goodwill impairment	(16.80%)	0.00%	0.00%
Change in fair value of contingent consideration	6.70%	0.00%	0.00%
Change in state apportionment	4.90%	0.00%	0.00%
Federal, state and foreign tax credits	2.20%	(1.50%)	(3.60%)
Valuation allowance	(3.00%)	0.00%	0.00%
Other permanent items	1.90%	(1.20%)	(3.10%)
Effective income tax rate	16.20%	24.70%	19.30%