Note 8 - Income Taxes (Details) - Deferred Tax Assets and Liabilities (USD $) In Thousands, unless otherwise specified	Dec. 31, 2013	Dec. 31, 2012
Deferred tax assets:
Research tax credits	$ 8,303	$ 4,930
Other expenses not currently deductible	3,204	2,133
Stock-based compensation	2,599	5,487
Litigation settlement	2,490
Net operating losses	627	291
Depreciation and amortization	291	317
Total deferred tax assets	17,514	13,158
Valuation allowance	(16,739)	(12,488)
Net deferred tax assets	$ 775	$ 670