Note 9 - Stock-based Compensation (Details) (USD $)	9 Months Ended
	Sep. 30, 2013	Dec. 31, 2011
Note 9 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number (in Shares)	3,569,189	2,162,114
Employee Service Share-based Compensation, Nonvested Awards, Compensation Not yet Recognized, Stock Options (in Dollars)	$ 20,645,000
Employee Service Share-based Compensation, Nonvested Awards, Compensation Cost Not yet Recognized, Period for Recognition	3 years 73 days
Employee Stock Purchase Plan Twenty Thirteen [Member]
Note 9 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Number of Shares Authorized (in Shares)	175,000
Number Of Shares Of Common Stock Reserved For Issuance Increase Description	The number of shares of common stock reserved for issuance will automatically increase on January 1 of each calendar year, from January 1, 2014 through January 1, 2023, by the least of (a) 1% of the total number of shares of common stock outstanding on December 31 of the preceding calendar year, (b) 200,000 shares, or (c) a number determined by our board of directors that is less than (a) and (b).
Equity Incentive Plan Twenty Thirteen [Member]
Note 9 - Stock-based Compensation (Details) [Line Items]
Common Stock, Capital Shares Reserved for Future Issuance (in Shares)	3,623,842
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number (in Shares)	1,457,608
Two Thousand Six Equity Incentive Plan [Member] | Non Employee Directors [Member]
Note 9 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	1 year
Two Thousand Six Equity Incentive Plan [Member]
Note 9 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number (in Shares)	1,102,002
Share Based Compensation Arrangement By Share Based Payment Award Stock Option Term	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	4 years
Amended And Restated Equity Incentive Plan [Member] | Non Employee Consultant [Member]
Note 9 - Stock-based Compensation (Details) [Line Items]
Share Based Compensation Arrangement By Share Based Payment Award Stock Option Term	2 years
Amended And Restated Equity Incentive Plan [Member]
Note 9 - Stock-based Compensation (Details) [Line Items]
Share-based Compensation Arrangement by Share-based Payment Award, Options, Outstanding, Number (in Shares)	1,009,579
Share Based Compensation Arrangement By Share Based Payment Award Stock Option Term	10 years
Share-based Compensation Arrangement by Share-based Payment Award, Award Vesting Period	2 years