Note 4 - Fair Value Measurements (Tables)

12 Months Ended

Dec. 31, 2016

Notes Tables

Schedule of Fair Value, Assets and Liabilities Measured on Recurring Basis [Table Text Block]

	Level 1		Level 2		Level 3		Total
Assets:
Cash and cash equivalents	$	21,352	$	—	$	—	$	21,352

	Level 1		Level 2		Level 3		Total
Assets:
Cash and cash equivalents	$	3,557	$	—	$	—	$	3,557
Liabilities:
Convertible preferred stock warrant liability	$	—	$	—	$	275	$	275
Maturity date preferred stock warrant liability	$	—	$	—	$	10	$	10
Convertible shareholder notes derivative liability	$	—	$	—	$	1,044	$	1,044

Fair Value, Liabilities Measured on Recurring Basis, Unobservable Input Reconciliation [Table Text Block]

	Convertible Preferred Stock Warrant Liability			Maturity Date Preferred Stock Warrant Liability			Convertible Shareholder Note Derivative Liability
Fair value December 31, 2015	$	275		$	10		$	1,044
Change in fair value		(250	)		(10	)		1,224
Exchange of convertible preferred stock warrants		(25	)		—			—
Conversion of convertible notes		—			—			(2,268	)
Fair value December 31, 2016	$	—		$	—		$	—