Note 13 - Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2019	Dec. 31, 2018	Dec. 31, 2017
Deferred Tax Assets [Member]
Balance	$ 5,563,000	$ 5,048,000	$ 8,023,000
Additions based on tax positions related to the current year	1,418,000	811,000	1,219,000
Additions for tax positions of prior years	907,000	209,000	342,000
Reductions for statute of limitation expirations	(475,000)	(505,000)	(1,682,000)
Revaluation due to federal tax reform			(2,854,000)
Balance	7,413,000	5,563,000	5,048,000
Liability for Unrecognized Tax Benefits [Member]
Balance	11,933,000	12,520,000	12,965,000
Additions based on tax positions related to the current year	1,418,000	811,000	1,219,000
Additions for tax positions of prior years	1,002,000	388,000	844,000
Reductions for statute of limitation expirations	(1,604,000)	(1,786,000)	(2,508,000)
Revaluation due to federal tax reform			0
Balance	12,749,000	11,933,000	12,520,000
Liability for Interest and Penalties [Member]
Balance	3,271,000	3,275,000	3,337,000
Additions based on tax positions related to the current year	0	0	0
Additions for tax positions of prior years	973,000	937,000	865,000
Reductions for statute of limitation expirations	(935,000)	(941,000)	(927,000)
Revaluation due to federal tax reform			0
Balance	3,309,000	3,271,000	3,275,000
Total Liability [Member]
Balance	15,204,000	15,795,000	16,302,000
Additions based on tax positions related to the current year	1,418,000	811,000	1,219,000
Additions for tax positions of prior years	1,975,000	1,325,000	1,709,000
Reductions for statute of limitation expirations	(2,539,000)	(2,727,000)	(3,435,000)
Revaluation due to federal tax reform			0
Balance	$ 16,058,000	$ 15,204,000	$ 15,795,000