Note 13 - Income Taxes - Reconciliation of Income Tax Expense (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Tax provision at federal statutory rate	$ 18,483,000	$ 15,726,000	$ 26,092,000
Tax expense from minority interest	61,000	71,000	204,000
State, net of federal benefit	(3,850,000)	(3,213,000)	(2,647,000)
Nondeductible expenses	207,000	478,000	230,000
Return to provision	(793,000)	(1,418,000)	0
Share based payments	(263,000)	(136,000)	(237,000)
Insurance expense	(82,000)	(128,000)	(103,000)
Revalue tax assets/liabilities due to federal tax reform	0	0	(8,488,000)
Other, net	128,000	15,000	(338,000)
Unrecognized tax benefits	512,000	586,000	613,000
Expiration of statute of limitations	(2,064,000)	(2,222,000)	(1,753,000)
Total increases (decreases)	1,556,000	459,000	(7,225,000)
Effective income tax expense	$ 20,039,000	$ 16,185,000	$ 18,867,000