Note 13 - Income Taxes - Reconciliation of Unrecognized Tax Benefits (Details) - USD ($)	12 Months Ended
	Dec. 31, 2018	Dec. 31, 2017	Dec. 31, 2016
Deferred Tax Assets [Member]
Balance	$ 5,048,000	$ 8,023,000	$ 7,818,000
Additions based on tax positions related to the current year	811,000	1,219,000	1,249,000
Additions for tax positions of prior years	209,000	342,000	481,000
Reductions for statute of limitation expirations	(505,000)	(1,682,000)	(1,525,000)
Revaluation due to federal tax reform		(2,854,000)
Balance	5,563,000	5,048,000	8,023,000
Liability for Unrecognized Tax Benefits [Member]
Balance	12,520,000	12,965,000	13,162,000
Additions based on tax positions related to the current year	811,000	1,219,000	1,249,000
Additions for tax positions of prior years	388,000	844,000	718,000
Reductions for statute of limitation expirations	(1,786,000)	(2,508,000)	(2,164,000)
Revaluation due to federal tax reform
Balance	11,933,000	12,520,000	12,965,000
Liability for Interest and Penalties [Member]
Balance	3,275,000	3,337,000	3,132,000
Additions based on tax positions related to the current year
Additions for tax positions of prior years	937,000	865,000	934,000
Reductions for statute of limitation expirations	(941,000)	(927,000)	(729,000)
Revaluation due to federal tax reform
Balance	3,271,000	3,275,000	3,337,000
Total Liability [Member]
Balance	15,795,000	16,302,000	16,294,000
Additions based on tax positions related to the current year	811,000	1,219,000	1,249,000
Additions for tax positions of prior years	1,325,000	1,709,000	1,652,000
Reductions for statute of limitation expirations	(2,727,000)	(3,435,000)	(2,893,000)
Revaluation due to federal tax reform
Balance	$ 15,204,000	$ 15,795,000	$ 16,302,000