Note 7 - Income Taxes (Details) - Reconciliation of Effective Tax Rate	12 Months Ended
	Dec. 31, 2014	Dec. 31, 2013	Dec. 31, 2012
Reconciliation of Effective Tax Rate [Abstract]
U.S. federal statutory income tax rate	34.00%	35.00%	35.00%
State tax rate, net of federal benefit	1.62%	1.57%	3.28%
Benefit for research and development credit	7.24%	19.91%	3.40%
Foreign rate differential	(1.04%)	(4.53%)	(1.49%)
Changes in unrecognized tax benefits	(0.53%)	2.60%	1.06%
Foreign income inclusion			(0.05%)
Income tax refund	0.08%	0.19%	1.07%
Stock-based compensation	(5.56%)	(34.33%)	(21.31%)
Meals and entertainment	(1.11%)	(2.10%)	(1.68%)
Tax effect of other comprehensive income			0.28%
Valuation allowance	(36.58%)	(17.82%)	(21.15%)
Other	(0.22%)	0.63%	(1.86%)
Effective tax rate	(2.10%)	1.12%	(3.45%)