Note 10 - Long-term Obligations - Schedule of Data Regarding the 6.25% Notes (Details) - 6.25% Convertible Notes Due 2018 [Member] - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Mar. 28, 2017	Jan. 29, 2016	May 10, 2011
Net carrying amount of the equity component	$ 686,000	$ 6,416,000			$ 8,500,000
Convertible notes	10,044,000	94,000,000	$ 94,000,000
Unamortized debt discount	$ 18,000	$ 2,271,000		$ 250,000
Amortization period remaining (months) (Month)	120 days	1 year 120 days
Net carrying amount of the convertible notes	$ 10,026,000	$ 91,729,000