Note 7 - Income Taxes (Tables)

12 Months Ended

Dec. 31, 2014

Income Tax Disclosure [Abstract]

Schedule of Effective Income Tax Rate Reconciliation [Table Text Block]

	2014			2013			2012
Income tax benefit at federal statutory rate (35%)	$	(15,816	)	$	(10,538	)	$	(13,678	)
State and local income taxes net of federal tax benefit		(1,286	)		(839	)		(1,470	)
Permanent items		258			738			754
Rate change		22			1,892			1,147
Expiration of attribute carryforwards		373			242			5,135
Research and development tax credits		(748	)		(1,206	)		829
Other		(115	)		1,144			281
Change in valuation allowance		17,312			8,567			7,002
Income tax expense	$	—		$	—		$	—

Schedule of Unrecognized Tax Benefits Roll Forward [Table Text Block]

	2014		2013
Balance at January 1,	$	284	$	—
Additions to current year tax positions		176		43
Additions to tax positions of prior years		12		241
Reductions for tax provisions of prior years		—		—
Balance at December 31,	$	472	$	284

Schedule of Deferred Tax Assets and Liabilities [Table Text Block]

	2014			2013
Deferred tax assets:
Net federal and state operating losses	$	135,922		$	119,940
Research and development credits		38,096			37,348
Fixed assets		1,073			1,119
Reserve for inventories		—			1,612
Deferred revenue		3,798			2,151
Stock-based compensation		7,086			5,282
Other		1,178			311
Total deferred tax assets		187,153			167,763
Deferred tax liabilities:
Foreign currency derivative		(2,285	)		(207	)
Total deferred tax liabilities		(2,285	)		(207	)
Valuation allowance		(184,868	)		(167,556	)
Net deferred tax assets	$	—		$	—