Note 4 - Balance Sheet Detail (Details Textual) - USD ($)	12 Months Ended
	Dec. 31, 2017	Dec. 31, 2016	Dec. 31, 2015
Capital Leased Assets, Gross	$ 1,600,000	$ 1,400,000
Capital Leases, Lessee Balance Sheet, Assets by Major Class, Accumulated Depreciation	725,000	492,000
Amortization of Intangible Assets	$ 2,000	$ 141,000	$ 452,000