Note 7 - Stockholders' Equity (Deficit) (Tables)

9 Months Ended

12 Months Ended

Sep. 30, 2019

Dec. 31, 2018

Notes Tables

Fair Value Measurement Inputs and Valuation Techniques [Table Text Block]

Expected term (years)	7
Expected volatility	55	%
Risk-free interest rate	2	%
Dividend rate	—

Expected term (years)	7
Expected volatility	55	%
Risk-free interest rate	2.0	%
Dividend rate	—

Share-based Payment Arrangement, Option, Activity [Table Text Block]

	Number of Shares			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (in years)		Intrinsic Value
Balance at December 31, 2018		7,954		$	1,707.30		7.69	$	—
Options expired		(433	)	$	3,015.01
Options forfeited		(105	)	$	1,929.52
Balance at September 30, 2019		7,416		$	1,316.32		7.05	$	—
Exercisable at September 30, 2019		7,181		$	1,300.40		7.05	$	—
Vested and expected to vest at September 30, 2019		7,416		$	1,316.32		7.05	$	—

	Number of Shares (in thousands)			Weighted Average Exercise Price		Weighted Average Remaining Contractual Life (in years)		Intrinsic Value (in thousands)
Balance at December 31, 2017		7,664		$	2,917.30			$	—
Options granted		3,100		$	16.70
Options exercised		—		$	—
Options expired		(2,551	)	$	2,725.80
Options forfeited		(259	)	$	3,493.70
Balance at December 31, 2018		(7,954	)	$	1,707.30		7.69	$	—
Exercisable at December 31, 2018		(4,330	)	$	2,469.70		6.41		—
Vested and expected to vest at December 31, 2018		(7,954	)	$	1,707.30		7.69	$	—

Share-based Payment Arrangement, Restricted Stock Unit, Activity [Table Text Block]

	Number of Shares			Weighted Average Grant Date Fair Value		Weighted Average Remaining Contractual Term
Awards outstanding at December 31, 2018		294,066		$	17.34		3.1
Awarded		764,151		$	1.24
Released		(96,444	)	$	17.86
Forfeited		(20,205	)	$	20.46
Awards outstanding at September 30, 2019		941,568		$	4.15		2.0

				Weighted Average		Weighted Average
				Grant Date		Remaining
	Number of			Fair		Contractual
	Shares			Value		Term
Awards outstanding at December 31, 2017		509		$	2,377.80		2.87
Awarded		297,753		$	15.00
Released		(128	)	$	2,739.70
Forfeited		(4,068	)	$	59.70
Awards outstanding at December 31, 2018		294,066		$	17.34		3.09