Note 12 - Income Taxes (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2016	Dec. 31, 2015	Dec. 31, 2014	Dec. 31, 2013
Adjustment to Additional Paid in Capital, Income Tax Effect from Share-based Compensation, Net	$ (1,096,000)	$ 1,942,000	$ 201,000
Unrecognized Tax Benefits, Period Increase (Decrease)	(2,164,000)	(2,551,000)	(2,059,000)
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	1,368,000	2,141,000	1,542,000
Effective Income Tax Rate Reconciliation, Benefit Resulting from Expiration of Applicable Statute Limitations, Amount	1,368,000	2,141,000	1,542,000
Significant Change in Unrecognized Tax Benefits is Reasonably Possible, Amount of Unrecorded Benefit	2,345,000
Income Tax Examination, Penalties and Interest Expense	$ 205,000	740,000	319,000
Earliest Tax Year [Member]
Open Tax Year	2013
Liability for Interest and Penalties [Member]
Unrecognized Tax Benefits, Reduction Resulting from Lapse of Applicable Statute of Limitations	$ 729,000	865,000	603,000
Unrecognized Tax Benefits	3,337,000	$ 3,132,000	$ 2,391,000	$ 2,072,000
Permanent Differences [Member]
Unrecognized Tax Benefits	$ 5,616,000