Note 8 - Income Taxes - Reconciliation of Income Tax Expense (Details) - USD ($) $ in Thousands	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Computed at federal statutory rate	$ 11,134	$ 13,949	$ 17,315
Computed at federal statutory rate, percentage	21.00%	35.00%	35.00%
State and local tax expense, net of federal benefit	$ 2,367	$ 2,226	$ 2,448
State and local tax expense, net of federal benefit, percentage	4.50%	5.60%	5.00%
Net permanent deduction and credit tax benefits from current year	$ (1,143)	$ (1,513)	$ (1,509)
Net permanent deduction and credit tax benefits from current year, percentage	(2.20%)	(3.80%)	(3.10%)
Net permanent deduction and credit tax benefits from prior years			$ (6,213)
Net permanent deduction and credit tax benefits from prior years, percentage			(12.60%)
Net uncertain tax positions excluding current permanent deduction and credit benefits	$ (3,756)	$ (373)
Net uncertain tax positions excluding current permanent deduction and credit benefits, percentage	(7.00%)	(0.90%)
Subsidiary basis write off	$ (3,423)
Subsidiary basis write off, percentage	(6.50%)
Equity compensation net tax windfall	$ (2,890)
Equity compensation net tax windfall, percentage	(5.50%)
State tax apportionment changes	$ (3,737)
State tax apportionment changes, percentage	(7.00%)
Disallowed executive compensation	$ 682
Disallowed executive compensation, percentage	1.30%
Tax Reform - revaluation of deferrals		$ (15,130)
Tax Reform - Revaluation of Deferrals, precentage		(38.00%)
Acquisition adjustments	$ (1,226)	$ (1,003)
Acquisition adjustments, percentage	(2.30%)	(2.50%)
Acquisition costs		$ 697	$ 203
Acquisition costs, precentage		1.70%	0.40%
Other, net	$ 20	$ 948	$ (409)
Other, net, percentage		2.40%	(0.80%)
Total income tax expense (benefit)	$ (1,972)	$ (199)	$ 11,835
Total income tax expense, percentage	(3.70%)	(0.50%)	23.90%